diff --git a/akka-docs-dev/rst/java/code/docs/http/javadsl/HttpClientExampleDocTest.java b/akka-docs-dev/rst/java/code/docs/http/javadsl/HttpClientExampleDocTest.java
index d654f8bd7f..44c41146c1 100644
--- a/akka-docs-dev/rst/java/code/docs/http/javadsl/HttpClientExampleDocTest.java
+++ b/akka-docs-dev/rst/java/code/docs/http/javadsl/HttpClientExampleDocTest.java
@@ -16,6 +16,7 @@ import akka.http.javadsl.model.*;
 import akka.http.javadsl.Http;
 import scala.util.Try;
 
+@SuppressWarnings("unused")
 public class HttpClientExampleDocTest {
 
     // compile only test
diff --git a/akka-docs-dev/rst/java/code/docs/http/javadsl/ModelDocTest.java b/akka-docs-dev/rst/java/code/docs/http/javadsl/ModelDocTest.java
index 30e3e7bc4c..782fcd0cbe 100644
--- a/akka-docs-dev/rst/java/code/docs/http/javadsl/ModelDocTest.java
+++ b/akka-docs-dev/rst/java/code/docs/http/javadsl/ModelDocTest.java
@@ -13,6 +13,7 @@ import akka.http.javadsl.model.*;
 import akka.http.javadsl.model.headers.*;
 //#import-model
 
+@SuppressWarnings("unused")
 public class ModelDocTest {
     @Test
     public void testConstructRequest() {
@@ -78,7 +79,7 @@ public class ModelDocTest {
     //#headers
 
     // a method that extracts basic HTTP credentials from a request
-    private Option<BasicHttpCredentials> getCredentialsOfRequest(HttpRequest request) {
+	private Option<BasicHttpCredentials> getCredentialsOfRequest(HttpRequest request) {
         Option<Authorization> auth = request.getHeader(Authorization.class);
         if (auth.isDefined() && auth.get().credentials() instanceof BasicHttpCredentials)
             return Option.some((BasicHttpCredentials) auth.get().credentials());
diff --git a/akka-docs-dev/rst/java/code/docs/http/javadsl/server/HttpServerExampleDocTest.java b/akka-docs-dev/rst/java/code/docs/http/javadsl/server/HttpServerExampleDocTest.java
index 6cbe9e9e0a..3d44d6ecf5 100644
--- a/akka-docs-dev/rst/java/code/docs/http/javadsl/server/HttpServerExampleDocTest.java
+++ b/akka-docs-dev/rst/java/code/docs/http/javadsl/server/HttpServerExampleDocTest.java
@@ -10,16 +10,12 @@ import akka.http.javadsl.Http;
 import akka.http.javadsl.IncomingConnection;
 import akka.http.javadsl.ServerBinding;
 import akka.http.javadsl.model.*;
-import akka.http.javadsl.model.ws.Websocket;
 import akka.japi.function.Function;
 import akka.japi.function.Procedure;
 import akka.stream.ActorMaterializer;
 import akka.stream.Materializer;
-import akka.stream.javadsl.Flow;
 import akka.stream.javadsl.Sink;
 import akka.stream.javadsl.Source;
-import org.junit.Test;
-import scala.Function1;
 import scala.concurrent.Await;
 import scala.concurrent.Future;
 import scala.concurrent.duration.FiniteDuration;
@@ -29,7 +25,7 @@ import java.io.InputStreamReader;
 import java.util.concurrent.TimeUnit;
 
 public class HttpServerExampleDocTest {
-    public static void bindingExample() {
+    public static void bindingExample() throws Exception {
         //#binding-example
         ActorSystem system = ActorSystem.create();
         Materializer materializer = ActorMaterializer.create(system);
@@ -47,6 +43,7 @@ public class HttpServerExampleDocTest {
                     }
                 })).run(materializer);
         //#binding-example
+        Await.result(serverBindingFuture, new FiniteDuration(3, TimeUnit.SECONDS));
     }
     public static void fullServerExample() throws Exception {
         //#full-server-example
diff --git a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/RejectionHandlerExamplesSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/RejectionHandlerExamplesSpec.scala
index 83a5c7c6d0..10710ee06a 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/RejectionHandlerExamplesSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/RejectionHandlerExamplesSpec.scala
@@ -23,13 +23,13 @@ object MyRejectionHandler {
         complete(HttpResponse(BadRequest, entity = "No cookies, no service!!!"))
       }
       .handle { case AuthorizationFailedRejection ⇒
-        complete(Forbidden, "You're out of your depth!")
+        complete((Forbidden, "You're out of your depth!"))
       }
       .handleAll[MethodRejection] { methodRejections ⇒
         val names = methodRejections.map(_.supported.name)
-        complete(MethodNotAllowed, s"Can't do that! Supported: ${names mkString " or "}!")
+        complete((MethodNotAllowed, s"Can't do that! Supported: ${names mkString " or "}!"))
       }
-      .handleNotFound { complete(NotFound, "Not here!") }
+      .handleNotFound { complete((NotFound, "Not here!")) }
       .result()
 
   object MyApp extends App {
diff --git a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/DebuggingDirectivesExamplesSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/DebuggingDirectivesExamplesSpec.scala
index 6ad0a8944f..4b98e8f49e 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/DebuggingDirectivesExamplesSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/DebuggingDirectivesExamplesSpec.scala
@@ -20,7 +20,7 @@ class DebuggingDirectivesExamplesSpec extends RoutingSpec {
     DebuggingDirectives.logRequest("get-user")
 
     // marks with "get-user", log with info level, HttpRequest.toString
-    DebuggingDirectives.logRequest("get-user", Logging.InfoLevel)
+    DebuggingDirectives.logRequest(("get-user", Logging.InfoLevel))
 
     // logs just the request method at debug level
     def requestMethod(req: HttpRequest): String = req.method.toString
@@ -46,7 +46,7 @@ class DebuggingDirectivesExamplesSpec extends RoutingSpec {
     DebuggingDirectives.logRequestResult("get-user")
 
     // marks with "get-user", log with info level, HttpRequest.toString, HttpResponse.toString
-    DebuggingDirectives.logRequestResult("get-user", Logging.InfoLevel)
+    DebuggingDirectives.logRequestResult(("get-user", Logging.InfoLevel))
 
     // logs just the request method and response status at info level
     def requestMethodAndResponseStatusAsInfo(req: HttpRequest): Any => Option[LogEntry] = {
@@ -72,7 +72,7 @@ class DebuggingDirectivesExamplesSpec extends RoutingSpec {
     DebuggingDirectives.logResult("get-user")
 
     // marks with "get-user", log with info level, HttpResponse.toString
-    DebuggingDirectives.logResult("get-user", Logging.InfoLevel)
+    DebuggingDirectives.logResult(("get-user", Logging.InfoLevel))
 
     // logs just the response status at debug level
     def responseStatus(res: Any): String = res match {
diff --git a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/ExecutionDirectivesExamplesSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/ExecutionDirectivesExamplesSpec.scala
index 4204e52a93..5b4716f130 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/ExecutionDirectivesExamplesSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/ExecutionDirectivesExamplesSpec.scala
@@ -11,7 +11,7 @@ import akka.http.scaladsl.server._
 class ExecutionDirectivesExamplesSpec extends RoutingSpec {
   "handleExceptions" in {
     val divByZeroHandler = ExceptionHandler {
-      case _: ArithmeticException => complete(StatusCodes.BadRequest, "You've got your arithmetic wrong, fool!")
+      case _: ArithmeticException => complete((StatusCodes.BadRequest, "You've got your arithmetic wrong, fool!"))
     }
     val route =
       path("divide" / IntNumber / IntNumber) { (a, b) =>
@@ -30,7 +30,7 @@ class ExecutionDirectivesExamplesSpec extends RoutingSpec {
   }
   "handleRejections" in {
     val totallyMissingHandler = RejectionHandler.newBuilder()
-      .handleNotFound { complete(StatusCodes.NotFound, "Oh man, what you are looking for is long gone.") }
+      .handleNotFound { complete((StatusCodes.NotFound, "Oh man, what you are looking for is long gone.")) }
       .result()
     val route =
       pathPrefix("handled") {
diff --git a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/FutureDirectivesExamplesSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/FutureDirectivesExamplesSpec.scala
index 3e8ac7850a..aa468b27af 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/FutureDirectivesExamplesSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/FutureDirectivesExamplesSpec.scala
@@ -23,7 +23,7 @@ class FutureDirectivesExamplesSpec extends RoutingSpec {
   implicit val myExceptionHandler =
     ExceptionHandler {
       case TestException => ctx =>
-        ctx.complete(InternalServerError, "Unsuccessful future!")
+        ctx.complete((InternalServerError, "Unsuccessful future!"))
     }
 
   val resourceActor = system.actorOf(Props(new Actor {
@@ -40,7 +40,7 @@ class FutureDirectivesExamplesSpec extends RoutingSpec {
       path("divide" / IntNumber / IntNumber) { (a, b) =>
         onComplete(divide(a, b)) {
           case Success(value) => complete(s"The result was $value")
-          case Failure(ex)    => complete(InternalServerError, s"An error occurred: ${ex.getMessage}")
+          case Failure(ex)    => complete((InternalServerError, s"An error occurred: ${ex.getMessage}"))
         }
       }
 
diff --git a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/PathDirectivesExamplesSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/PathDirectivesExamplesSpec.scala
index 2e3cc7166b..79bb8bdc7b 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/PathDirectivesExamplesSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/PathDirectivesExamplesSpec.scala
@@ -16,7 +16,7 @@ class PathDirectivesExamplesSpec extends RoutingSpec {
 
   //# path-dsl
   // matches /foo/
-  path("foo" /)
+  path("foo"./)
 
   // matches e.g. /foo/123 and extracts "123" as a String
   path("foo" / """\d+""".r)
diff --git a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/RouteDirectivesExamplesSpec.scala b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/RouteDirectivesExamplesSpec.scala
index 9ee5bdb3c3..d4c6c9b5f5 100644
--- a/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/RouteDirectivesExamplesSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/http/scaladsl/server/directives/RouteDirectivesExamplesSpec.scala
@@ -16,7 +16,7 @@ class RouteDirectivesExamplesSpec extends RoutingSpec {
         complete(HttpResponse(entity = "foo"))
       } ~
         path("b") {
-          complete(StatusCodes.Created, "bar")
+          complete((StatusCodes.Created, "bar"))
         } ~
         (path("c") & complete("baz")) // `&` also works with `complete` as the 2nd argument
 
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/FlowDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/FlowDocSpec.scala
index f73f7c3ac9..5e20b5c389 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/FlowDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/FlowDocSpec.scala
@@ -199,7 +199,7 @@ class FlowDocSpec extends AkkaSpec {
     val (promise, cancellable, future) = r11.run()
 
     // Type inference works as expected
-    promise.success(0)
+    promise.success(())
     cancellable.cancel()
     future.map(_ + 3)
 
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/FlowGraphDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/FlowGraphDocSpec.scala
index 84b3d447bd..92ede6b22c 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/FlowGraphDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/FlowGraphDocSpec.scala
@@ -141,8 +141,9 @@ class FlowGraphDocSpec extends AkkaSpec {
         outlets: immutable.Seq[Outlet[_]]) = {
         assert(inlets.size == this.inlets.size)
         assert(outlets.size == this.outlets.size)
-        // This is why order matters when overriding inlets and outlets
-        PriorityWorkerPoolShape(inlets(0), inlets(1), outlets(0))
+        // This is why order matters when overriding inlets and outlets.
+        // The "[Nothing, Any]" is equivalent to casting the Inlets/Outlets.
+        PriorityWorkerPoolShape[Nothing, Any](inlets(0), inlets(1), outlets(0))
       }
     }
     //#flow-graph-components-shape
diff --git a/akka-docs-dev/rst/scala/code/docs/stream/io/StreamFileDocSpec.scala b/akka-docs-dev/rst/scala/code/docs/stream/io/StreamFileDocSpec.scala
index 3ba5bfe513..6b3543799d 100644
--- a/akka-docs-dev/rst/scala/code/docs/stream/io/StreamFileDocSpec.scala
+++ b/akka-docs-dev/rst/scala/code/docs/stream/io/StreamFileDocSpec.scala
@@ -32,6 +32,7 @@ class StreamFileDocSpec extends AkkaSpec(UnboundedMailboxConfig) {
     //#file-source
     import akka.stream.io._
     //#file-source
+    Thread.sleep(0) // needs a statement here for valid syntax and to avoid "unused" warnings
   }
 
   {
diff --git a/akka-http-core/src/main/java/akka/http/impl/util/Util.java b/akka-http-core/src/main/java/akka/http/impl/util/Util.java
index 3c0d8b06b8..8ba7217116 100644
--- a/akka-http-core/src/main/java/akka/http/impl/util/Util.java
+++ b/akka-http-core/src/main/java/akka/http/impl/util/Util.java
@@ -23,17 +23,17 @@ public abstract class Util {
     // needed to provide covariant conversions that the Java interfaces don't provide automatically.
     // The alternative would be having to cast around everywhere instead of doing it here in a central place.
     public static <U, T extends U> Option<U> convertOption(scala.Option<T> o) {
-        return (Option<U>)(Option) akka.japi.Option.fromScalaOption(o);
+        return (Option<U>)(Object) akka.japi.Option.fromScalaOption(o);
     }
     @SuppressWarnings("unchecked") // no support for covariance of Publisher in Java
     // needed to provide covariant conversions that the Java interfaces don't provide automatically.
     // The alternative would be having to cast around everywhere instead of doing it here in a central place.
     public static <U, T extends U> Source<U, scala.Unit> convertPublisher(Source<T, scala.Unit> p) {
-        return (Source<U, scala.Unit>)(Source) p;
+        return (Source<U, scala.Unit>)(Object) p;
     }
     @SuppressWarnings("unchecked")
     public static <T, U extends T> Source<U, scala.Unit> upcastSource(Source<T, scala.Unit> p) {
-        return (Source<U, scala.Unit>)(Source) p;
+        return (Source<U, scala.Unit>)(Object) p;
     }
     @SuppressWarnings("unchecked")
     public static scala.collection.immutable.Map<String, String> convertMapToScala(Map<String, String> map) {
diff --git a/akka-http-core/src/main/java/akka/http/javadsl/model/ContentRange.java b/akka-http-core/src/main/java/akka/http/javadsl/model/ContentRange.java
index 26d5ecc1ef..c21e286a61 100644
--- a/akka-http-core/src/main/java/akka/http/javadsl/model/ContentRange.java
+++ b/akka-http-core/src/main/java/akka/http/javadsl/model/ContentRange.java
@@ -27,7 +27,7 @@ public abstract class ContentRange {
     }
     @SuppressWarnings("unchecked")
     public static ContentRange create(long first, long last, Option<Long> instanceLength) {
-        return ContentRange$.MODULE$.apply(first, last, ((Option<Object>) (Option) instanceLength).asScala());
+        return ContentRange$.MODULE$.apply(first, last, ((Option<Object>) (Object) instanceLength).asScala());
     }
     public static ContentRange createUnsatisfiable(long length) {
         return new akka.http.scaladsl.model.ContentRange.Unsatisfiable(length);
diff --git a/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpChallenge.java b/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpChallenge.java
index 643de1da96..772b424a44 100644
--- a/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpChallenge.java
+++ b/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpChallenge.java
@@ -4,7 +4,6 @@
 
 package akka.http.javadsl.model.headers;
 
-import akka.http.scaladsl.model.headers.HttpChallenge$;
 import akka.http.impl.util.Util;
 
 import java.util.Map;
diff --git a/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpCookie.java b/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpCookie.java
index b7d1f2cc00..8b83d50dcd 100644
--- a/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpCookie.java
+++ b/akka-http-core/src/main/java/akka/http/javadsl/model/headers/HttpCookie.java
@@ -50,7 +50,7 @@ public abstract class HttpCookie {
         return new akka.http.scaladsl.model.headers.HttpCookie(
                 name, value,
                 Util.<DateTime, akka.http.scaladsl.model.DateTime>convertOptionToScala(expires),
-                ((Option<Object>) (Option) maxAge).asScala(),
+                ((Option<Object>) (Object) maxAge).asScala(),
                 domain.asScala(),
                 path.asScala(),
                 secure,
diff --git a/akka-http-core/src/main/java/akka/http/javadsl/model/headers/LinkParam.java b/akka-http-core/src/main/java/akka/http/javadsl/model/headers/LinkParam.java
index 14c111a5f8..f82dae8467 100644
--- a/akka-http-core/src/main/java/akka/http/javadsl/model/headers/LinkParam.java
+++ b/akka-http-core/src/main/java/akka/http/javadsl/model/headers/LinkParam.java
@@ -4,10 +4,6 @@
 
 package akka.http.javadsl.model.headers;
 
-import akka.http.javadsl.model.MediaType;
-import akka.http.javadsl.model.Uri;
-import akka.http.impl.util.Util;
-
 public abstract class LinkParam {
     public abstract String key();
     public abstract Object value();
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/client/OutgoingConnectionBlueprint.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/client/OutgoingConnectionBlueprint.scala
index 07c1c7f9ef..3e9631d5b0 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/client/OutgoingConnectionBlueprint.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/client/OutgoingConnectionBlueprint.scala
@@ -126,6 +126,7 @@ private[http] object OutgoingConnectionBlueprint {
           case (ctx, `terminationBackchannelInput`) ⇒
             ctx.finish()
             SameState
+          case (_, _) ⇒ SameState
         },
         onUpstreamFailure = defaultCompletionHandling.onUpstreamFailure)
     }
@@ -220,6 +221,7 @@ private[http] object OutgoingConnectionBlueprint {
               ctx.fail(new ResponseParsingError(parser.onPull().asInstanceOf[ErrorOutput]))
             }
             SameState
+          case (_, _) ⇒ SameState
         },
         onUpstreamFailure = defaultCompletionHandling.onUpstreamFailure)
     }
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/server/HttpServerBluePrint.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/server/HttpServerBluePrint.scala
index 361288c970..bacd72e1c4 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/server/HttpServerBluePrint.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/server/HttpServerBluePrint.scala
@@ -204,10 +204,14 @@ private[http] object HttpServerBluePrint {
             }
 
           case (ctx, _, OneHundredContinue) ⇒
-            assert(requestStart.expect100ContinueResponsePending)
+            require(requestStart.expect100ContinueResponsePending)
             ctx.emit(ResponseRenderingContext(HttpResponse(StatusCodes.Continue)))
             requestStart = requestStart.copy(expect100ContinueResponsePending = false)
             SameState
+
+          case (ctx, _, msg) ⇒
+            ctx.fail(new IllegalStateException(s"unexpected message of type [${msg.getClass}], expecting only HttpResponse or OneHundredContinue"))
+            SameState
         }
 
       val waitingForApplicationResponseCompletionHandling = CompletionHandling(
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventParser.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventParser.scala
index 927b2a3a67..73a0686313 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventParser.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventParser.scala
@@ -99,7 +99,7 @@ private[http] class FrameEventParser extends ByteStringParserStage[FrameEvent] {
           remaining -= elem.size
           ctx.push(FrameData(elem, lastPart = false))
         } else {
-          assert(remaining <= Int.MaxValue) // safe because, remaining <= elem.size <= Int.MaxValue
+          require(remaining <= Int.MaxValue) // safe because, remaining <= elem.size <= Int.MaxValue
           val frameData = elem.take(remaining.toInt)
           val remainingData = elem.drop(remaining.toInt)
 
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventRenderer.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventRenderer.scala
index ab0c0da679..f74df264d9 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventRenderer.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameEventRenderer.scala
@@ -20,10 +20,13 @@ private[http] class FrameEventRenderer extends StatefulStage[FrameEvent, ByteStr
   object Idle extends State {
     def onPush(elem: FrameEvent, ctx: Context[ByteString]): SyncDirective = elem match {
       case start @ FrameStart(header, data) ⇒
-        assert(header.length >= data.size)
+        require(header.length >= data.size)
         if (!start.lastPart && header.length > 0) become(renderData(header.length - data.length, this))
 
         ctx.push(renderStart(start))
+
+      case f: FrameData ⇒
+        ctx.fail(new IllegalStateException("unexpected FrameData (need FrameStart first)"))
     }
   }
 
@@ -43,6 +46,9 @@ private[http] class FrameEventRenderer extends StatefulStage[FrameEvent, ByteStr
             remaining -= data.size
             ctx.push(data)
           }
+
+        case f: FrameStart ⇒
+          ctx.fail(new IllegalStateException("unexpected FrameStart (need more FrameData first)"))
       }
     }
 
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameHandler.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameHandler.scala
index dd4dac5714..d9ec07e1b7 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameHandler.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/FrameHandler.scala
@@ -106,10 +106,11 @@ private[http] object FrameHandler {
           val closeCode = FrameEventParser.parseCloseCode(data)
           emit(Iterator(Left(PeerClosed(closeCode)), Right(PeerClosed(closeCode))), ctx, WaitForPeerTcpClose)
         case Opcode.Other(o) ⇒ closeWithCode(Protocol.CloseCodes.ProtocolError, "Unsupported opcode")
+        case other           ⇒ ctx.fail(new IllegalStateException(s"unexpected message of type [${other.getClass.getName}] when expecting ControlFrame"))
       }
     }
     private def collectControlFrame(start: FrameStart, nextState: State)(implicit ctx: Ctx): SyncDirective = {
-      assert(!start.isFullMessage)
+      require(!start.isFullMessage)
       become(new CollectingControlFrame(start.header.opcode, start.data, nextState))
       ctx.pull()
     }
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Masking.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Masking.scala
index bb6b53494f..730f782a42 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Masking.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Masking.scala
@@ -57,6 +57,8 @@ private[http] object Masking {
               become(new Running(mask))
               current.onPush(start.copy(header = setNewMask(header, mask)), ctx)
             }
+          case _: FrameData ⇒
+            ctx.fail(new IllegalStateException("unexpected FrameData (need FrameStart first)"))
         }
     }
     class Running(initialMask: Int) extends State {
diff --git a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Utf8Encoder.scala b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Utf8Encoder.scala
index a129fd375d..74d65d50ab 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Utf8Encoder.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/engine/ws/Utf8Encoder.scala
@@ -24,7 +24,6 @@ private[http] class Utf8Encoder extends PushStage[String, ByteString] {
     val builder = new ByteStringBuilder
 
     def b(v: Int): Unit = {
-      assert((v & 0xff) == v)
       builder += v.toByte
     }
 
diff --git a/akka-http-core/src/main/scala/akka/http/impl/util/package.scala b/akka-http-core/src/main/scala/akka/http/impl/util/package.scala
index 1737e472d2..4d90d50aa3 100644
--- a/akka-http-core/src/main/scala/akka/http/impl/util/package.scala
+++ b/akka-http-core/src/main/scala/akka/http/impl/util/package.scala
@@ -44,7 +44,7 @@ package object util {
     new EnhancedInetSocketAddress(address)
   private[http] implicit def enhanceByteStrings(byteStrings: TraversableOnce[ByteString]): EnhancedByteStringTraversableOnce =
     new EnhancedByteStringTraversableOnce(byteStrings)
-  private[http] implicit def enhanceByteStrings[Mat](byteStrings: Source[ByteString, Mat]): EnhancedByteStringSource[Mat] =
+  private[http] implicit def enhanceByteStringsMat[Mat](byteStrings: Source[ByteString, Mat]): EnhancedByteStringSource[Mat] =
     new EnhancedByteStringSource(byteStrings)
 
   private[http] def headAndTailFlow[T]: Flow[Source[T, Any], (T, Source[T, Unit]), Unit] =
diff --git a/akka-http-core/src/test/scala/akka/http/impl/engine/client/ConnectionPoolSpec.scala b/akka-http-core/src/test/scala/akka/http/impl/engine/client/ConnectionPoolSpec.scala
index e1463b1118..a3551e7606 100644
--- a/akka-http-core/src/test/scala/akka/http/impl/engine/client/ConnectionPoolSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/impl/engine/client/ConnectionPoolSpec.scala
@@ -209,8 +209,8 @@ class ConnectionPoolSpec extends AkkaSpec("""
       val PoolGateway.Running(_, shutdownStartedPromise, shutdownCompletedPromise) = gateway.currentState
       shutdownStartedPromise.isCompleted shouldEqual false
       shutdownCompletedPromise.isCompleted shouldEqual false
-      Await.result(shutdownStartedPromise.future, 1500.millis) shouldEqual () // verify shutdown start (after idle)
-      Await.result(shutdownCompletedPromise.future, 1500.millis) shouldEqual () // verify shutdown completed
+      Await.result(shutdownStartedPromise.future, 1500.millis) // verify shutdown start (after idle)
+      Await.result(shutdownCompletedPromise.future, 1500.millis) // verify shutdown completed
     }
 
     "transparently restart after idle shutdown" in new TestSetup() {
@@ -218,7 +218,7 @@ class ConnectionPoolSpec extends AkkaSpec("""
 
       val gateway = Await.result(hcp.gatewayFuture, 500.millis)
       val PoolGateway.Running(_, _, shutdownCompletedPromise) = gateway.currentState
-      Await.result(shutdownCompletedPromise.future, 1500.millis) shouldEqual () // verify shutdown completed
+      Await.result(shutdownCompletedPromise.future, 1500.millis) // verify shutdown completed
 
       requestIn.sendNext(HttpRequest(uri = "/") -> 42)
 
diff --git a/akka-http-testkit/src/main/scala/akka/http/javadsl/testkit/RouteTest.scala b/akka-http-testkit/src/main/scala/akka/http/javadsl/testkit/RouteTest.scala
index a68bce8403..c1624a6b3b 100644
--- a/akka-http-testkit/src/main/scala/akka/http/javadsl/testkit/RouteTest.scala
+++ b/akka-http-testkit/src/main/scala/akka/http/javadsl/testkit/RouteTest.scala
@@ -44,6 +44,7 @@ abstract class RouteTest extends AllDirectives {
 
     result.awaitResult(awaitDuration) match {
       case RouteResult.Complete(response) ⇒ createTestResponse(response)
+      case RouteResult.Rejected(ex)       ⇒ throw new AssertionError("got unexpected rejection: " + ex)
     }
   }
 
diff --git a/akka-http-tests-java8/src/main/java/akka/http/javadsl/server/examples/simple/SimpleServerApp8.java b/akka-http-tests-java8/src/main/java/akka/http/javadsl/server/examples/simple/SimpleServerApp8.java
index 3be7bfea36..8d36bc6429 100644
--- a/akka-http-tests-java8/src/main/java/akka/http/javadsl/server/examples/simple/SimpleServerApp8.java
+++ b/akka-http-tests-java8/src/main/java/akka/http/javadsl/server/examples/simple/SimpleServerApp8.java
@@ -40,6 +40,7 @@ public class SimpleServerApp8 extends HttpApp {
     @Override
     public Route createRoute() {
         Handler addHandler = new Handler() {
+            static final long serialVersionUID = 1L;
             @Override
             public RouteResult apply(RequestContext ctx) {
                 int xVal = x.get(ctx);
@@ -49,6 +50,7 @@ public class SimpleServerApp8 extends HttpApp {
             }
         };
         Handler2<Integer, Integer> subtractHandler = new Handler2<Integer, Integer>() {
+            static final long serialVersionUID = 1L;
             public RouteResult apply(RequestContext ctx, Integer xVal, Integer yVal) {
                 int result = xVal - yVal;
                 return ctx.complete(String.format("%d - %d = %d", xVal, yVal, result));
diff --git a/akka-http-tests-java8/src/test/java/docs/http/javadsl/server/HandlerExampleDocTest.java b/akka-http-tests-java8/src/test/java/docs/http/javadsl/server/HandlerExampleDocTest.java
index fdcb15e02d..87e003ed1b 100644
--- a/akka-http-tests-java8/src/test/java/docs/http/javadsl/server/HandlerExampleDocTest.java
+++ b/akka-http-tests-java8/src/test/java/docs/http/javadsl/server/HandlerExampleDocTest.java
@@ -11,13 +11,10 @@ import akka.http.javadsl.server.values.Parameters;
 import akka.http.javadsl.server.values.PathMatchers;
 import akka.http.javadsl.testkit.JUnitRouteTest;
 import akka.http.javadsl.testkit.TestRoute;
-import akka.japi.function.Function;
 import org.junit.Test;
 import scala.concurrent.ExecutionContext;
 import scala.concurrent.Future;
 
-import java.util.concurrent.Callable;
-
 public class HandlerExampleDocTest extends JUnitRouteTest {
     @Test
     public void testSimpleHandler() {
@@ -25,6 +22,7 @@ public class HandlerExampleDocTest extends JUnitRouteTest {
         class TestHandler extends akka.http.javadsl.server.AllDirectives {
             //#simple-handler
             Handler handler = new Handler() {
+                static final long serialVersionUID = 1L;
                 @Override
                 public RouteResult apply(RequestContext ctx) {
                     return ctx.complete("This was a " + ctx.request().method().value()  +
@@ -75,6 +73,7 @@ public class HandlerExampleDocTest extends JUnitRouteTest {
             //#handler2
             final Handler2<Integer, Integer> multiply =
                 new Handler2<Integer, Integer>() {
+                    static final long serialVersionUID = 1L;
                     @Override
                     public RouteResult apply(RequestContext ctx, Integer x, Integer y) {
                         int result = x * y;
diff --git a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/CacheConditionDirectivesSpec.scala b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/CacheConditionDirectivesSpec.scala
index 4c7cd631dd..f18b017982 100644
--- a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/CacheConditionDirectivesSpec.scala
+++ b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/CacheConditionDirectivesSpec.scala
@@ -146,7 +146,7 @@ class CacheConditionDirectivesSpec extends RoutingSpec {
 
     "not filter out a `Range` header if `If-Range` does match the timestamp" in {
       Get() ~> `If-Range`(timestamp) ~> Range(ByteRange(0, 10)) ~> {
-        (conditional(tag, timestamp) & optionalHeaderValueByType[Range]()) { echoComplete }
+        (conditional(tag, timestamp) & optionalHeaderValueByType[Range](())) { echoComplete }
       } ~> check {
         status shouldEqual OK
         responseAs[String] should startWith("Some")
@@ -155,7 +155,7 @@ class CacheConditionDirectivesSpec extends RoutingSpec {
 
     "filter out a `Range` header if `If-Range` doesn't match the timestamp" in {
       Get() ~> `If-Range`(timestamp - 1000) ~> Range(ByteRange(0, 10)) ~> {
-        (conditional(tag, timestamp) & optionalHeaderValueByType[Range]()) { echoComplete }
+        (conditional(tag, timestamp) & optionalHeaderValueByType[Range](())) { echoComplete }
       } ~> check {
         status shouldEqual OK
         responseAs[String] shouldEqual "None"
@@ -164,7 +164,7 @@ class CacheConditionDirectivesSpec extends RoutingSpec {
 
     "not filter out a `Range` header if `If-Range` does match the ETag" in {
       Get() ~> `If-Range`(tag) ~> Range(ByteRange(0, 10)) ~> {
-        (conditional(tag, timestamp) & optionalHeaderValueByType[Range]()) { echoComplete }
+        (conditional(tag, timestamp) & optionalHeaderValueByType[Range](())) { echoComplete }
       } ~> check {
         status shouldEqual OK
         responseAs[String] should startWith("Some")
@@ -173,7 +173,7 @@ class CacheConditionDirectivesSpec extends RoutingSpec {
 
     "filter out a `Range` header if `If-Range` doesn't match the ETag" in {
       Get() ~> `If-Range`(EntityTag("other")) ~> Range(ByteRange(0, 10)) ~> {
-        (conditional(tag, timestamp) & optionalHeaderValueByType[Range]()) { echoComplete }
+        (conditional(tag, timestamp) & optionalHeaderValueByType[Range](())) { echoComplete }
       } ~> check {
         status shouldEqual OK
         responseAs[String] shouldEqual "None"
diff --git a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/ExecutionDirectivesSpec.scala b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/ExecutionDirectivesSpec.scala
index a9e82279f4..86e5cd6eb7 100644
--- a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/ExecutionDirectivesSpec.scala
+++ b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/ExecutionDirectivesSpec.scala
@@ -14,7 +14,7 @@ class ExecutionDirectivesSpec extends RoutingSpec {
   object MyException extends RuntimeException
   val handler =
     ExceptionHandler {
-      case MyException ⇒ complete(500, "Pling! Plong! Something went wrong!!!")
+      case MyException ⇒ complete((500, "Pling! Plong! Something went wrong!!!"))
     }
 
   "The `handleExceptions` directive" should {
diff --git a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/FutureDirectivesSpec.scala b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/FutureDirectivesSpec.scala
index 6616d9eca0..fc0c6e7130 100644
--- a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/FutureDirectivesSpec.scala
+++ b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/directives/FutureDirectivesSpec.scala
@@ -16,7 +16,7 @@ class FutureDirectivesSpec extends RoutingSpec {
   def throwTestException[T](msgPrefix: String): T ⇒ Nothing = t ⇒ throw new TestException(msgPrefix + t)
 
   implicit val exceptionHandler = ExceptionHandler {
-    case e: TestException ⇒ complete(StatusCodes.InternalServerError, "Oops. " + e)
+    case e: TestException ⇒ complete((StatusCodes.InternalServerError, "Oops. " + e))
   }
 
   "The `onComplete` directive" should {
@@ -39,13 +39,13 @@ class FutureDirectivesSpec extends RoutingSpec {
     "catch an exception in the success case" in {
       Get() ~> onComplete(Future.successful("ok")) { throwTestException("EX when ") } ~> check {
         status shouldEqual StatusCodes.InternalServerError
-        responseAs[String] shouldEqual "Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$TestException: EX when Success(ok)"
+        responseAs[String] shouldEqual s"Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$$TestException: EX when Success(ok)"
       }
     }
     "catch an exception in the failure case" in {
       Get() ~> onComplete(Future.failed[String](new RuntimeException("no"))) { throwTestException("EX when ") } ~> check {
         status shouldEqual StatusCodes.InternalServerError
-        responseAs[String] shouldEqual "Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$TestException: EX when Failure(java.lang.RuntimeException: no)"
+        responseAs[String] shouldEqual s"Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$$TestException: EX when Failure(java.lang.RuntimeException: no)"
       }
     }
   }
@@ -64,7 +64,7 @@ class FutureDirectivesSpec extends RoutingSpec {
     "catch an exception in the success case" in {
       Get() ~> onSuccess(Future.successful("ok")) { throwTestException("EX when ") } ~> check {
         status shouldEqual StatusCodes.InternalServerError
-        responseAs[String] shouldEqual "Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$TestException: EX when ok"
+        responseAs[String] shouldEqual s"Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$$TestException: EX when ok"
       }
     }
     "catch an exception in the failure case" in {
@@ -99,7 +99,7 @@ class FutureDirectivesSpec extends RoutingSpec {
     "catch an exception during recovery" in {
       Get() ~> completeOrRecoverWith(Future.failed[String](TestException)) { throwTestException("EX when ") } ~> check {
         status shouldEqual StatusCodes.InternalServerError
-        responseAs[String] shouldEqual "Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$TestException: EX when akka.http.scaladsl.server.directives.FutureDirectivesSpec$TestException$: XXX"
+        responseAs[String] shouldEqual s"Oops. akka.http.scaladsl.server.directives.FutureDirectivesSpec$$TestException: EX when akka.http.scaladsl.server.directives.FutureDirectivesSpec$$TestException$$: XXX"
       }
     }
   }
diff --git a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/util/TupleOpsSpec.scala b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/util/TupleOpsSpec.scala
index f1a36af50f..276f32b44b 100644
--- a/akka-http-tests/src/test/scala/akka/http/scaladsl/server/util/TupleOpsSpec.scala
+++ b/akka-http-tests/src/test/scala/akka/http/scaladsl/server/util/TupleOpsSpec.scala
@@ -21,9 +21,9 @@ class TupleOpsSpec extends WordSpec with Matchers {
     }
 
     "support joining tuples" in {
-      (1, 'X2, "3") join () shouldEqual (1, 'X2, "3")
-      () join (1, 'X2, "3") shouldEqual (1, 'X2, "3")
-      (1, 'X2, "3") join (4.0, 5L) shouldEqual (1, 'X2, "3", 4.0, 5L)
+      (1, 'X2, "3") join (()) shouldEqual ((1, 'X2, "3"))
+      () join ((1, 'X2, "3")) shouldEqual ((1, 'X2, "3"))
+      (1, 'X2, "3") join ((4.0, 5L)) shouldEqual ((1, 'X2, "3", 4.0, 5L))
     }
   }
 }
\ No newline at end of file
diff --git a/akka-http/src/main/scala/akka/http/impl/server/RouteImplementation.scala b/akka-http/src/main/scala/akka/http/impl/server/RouteImplementation.scala
index 4519a88a3f..2a0794bcac 100644
--- a/akka-http/src/main/scala/akka/http/impl/server/RouteImplementation.scala
+++ b/akka-http/src/main/scala/akka/http/impl/server/RouteImplementation.scala
@@ -151,7 +151,7 @@ private[http] object RouteImplementation extends Directives with server.RouteCon
         (requestValToDirective(dyn.value1) & requestValToDirective(dyn.value2))(runToRoute)
 
       case o: OpaqueRoute ⇒ (ctx ⇒ o.handle(new RequestContextImpl(ctx)).asInstanceOf[RouteResultImpl].underlying)
-      case p: Product     ⇒ extractExecutionContext { implicit ec ⇒ complete(500, s"Not implemented: ${p.productPrefix}") }
+      case p: Product     ⇒ extractExecutionContext { implicit ec ⇒ complete((500, s"Not implemented: ${p.productPrefix}")) }
     }
   }
   def pathMatcherDirective[T](matchers: immutable.Seq[PathMatcher[_]],
diff --git a/akka-http/src/main/scala/akka/http/javadsl/server/values/Header.scala b/akka-http/src/main/scala/akka/http/javadsl/server/values/Header.scala
index 5cb079ae27..542b784125 100644
--- a/akka-http/src/main/scala/akka/http/javadsl/server/values/Header.scala
+++ b/akka-http/src/main/scala/akka/http/javadsl/server/values/Header.scala
@@ -28,7 +28,7 @@ object Headers {
     HeaderImpl[HttpHeader](name, _ ⇒ optionalHeaderInstanceByName(name.toLowerCase()), classTag[HttpHeader])
 
   def byClass[T <: HttpHeader](clazz: Class[T]): Header[T] =
-    HeaderImpl[T](clazz.getSimpleName, ct ⇒ optionalHeaderValueByType(ClassMagnet()(ct)), ClassTag(clazz))
+    HeaderImpl[T](clazz.getSimpleName, ct ⇒ optionalHeaderValueByType(ClassMagnet(ct)), ClassTag(clazz))
 
   private def optionalHeaderInstanceByName(lowercaseName: String): Directive1[Option[model.HttpHeader]] =
     extract(_.request.headers.collectFirst {
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/coding/Deflate.scala b/akka-http/src/main/scala/akka/http/scaladsl/coding/Deflate.scala
index 1a97443fef..4762bfa152 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/coding/Deflate.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/coding/Deflate.scala
@@ -43,7 +43,7 @@ class DeflateCompressor extends Compressor {
   override final def finish(): ByteString = finishWithBuffer(newTempBuffer())
 
   protected def compressWithBuffer(input: ByteString, buffer: Array[Byte]): ByteString = {
-    assert(deflater.needsInput())
+    require(deflater.needsInput())
     deflater.setInput(input.toArray)
     drainDeflater(deflater, buffer)
   }
@@ -108,7 +108,7 @@ private[http] object DeflateCompressor {
       result ++= ByteString.fromArray(buffer, 0, len)
       drainDeflater(deflater, buffer, result)
     } else {
-      assert(deflater.needsInput())
+      require(deflater.needsInput())
       result.result()
     }
   }
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/Directive.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/Directive.scala
index f0627d65d1..a2f0c0e34b 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/Directive.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/Directive.scala
@@ -101,7 +101,7 @@ object Directive {
   /**
    * A Directive that always passes the request on to its inner route (i.e. does nothing).
    */
-  val Empty: Directive0 = Directive(_())
+  val Empty: Directive0 = Directive(_(()))
 
   /**
    * Adds `apply` to all Directives with 1 or more extractions,
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/ExceptionHandler.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/ExceptionHandler.scala
index 3b9ac54dae..278f173fa1 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/ExceptionHandler.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/ExceptionHandler.scala
@@ -41,7 +41,7 @@ object ExceptionHandler {
       case IllegalRequestException(info, status) ⇒ ctx ⇒ {
         ctx.log.warning("Illegal request {}\n\t{}\n\tCompleting with '{}' response",
           ctx.request, info.formatPretty, status)
-        ctx.complete(status, info.format(settings.verboseErrorMessages))
+        ctx.complete((status, info.format(settings.verboseErrorMessages)))
       }
       case NonFatal(e) ⇒ ctx ⇒ {
         ctx.log.error(e, "Error during processing of request {}", ctx.request)
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/PathMatcher.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/PathMatcher.scala
index e63d36341e..4e8d8f7f84 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/PathMatcher.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/PathMatcher.scala
@@ -275,7 +275,7 @@ trait ImplicitPathMatcherConstruction {
    */
   implicit def valueMap2PathMatcher[T](valueMap: Map[String, T]): PathMatcher1[T] =
     if (valueMap.isEmpty) PathMatchers.nothingMatcher
-    else valueMap.map { case (prefix, value) ⇒ stringExtractionPair2PathMatcher(prefix, value) }.reduceLeft(_ | _)
+    else valueMap.map { case (prefix, value) ⇒ stringExtractionPair2PathMatcher((prefix, value)) }.reduceLeft(_ | _)
 }
 
 trait PathMatchers {
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/RejectionHandler.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/RejectionHandler.scala
index dc3d88f871..72ced368e9 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/RejectionHandler.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/RejectionHandler.scala
@@ -117,60 +117,60 @@ object RejectionHandler {
     newBuilder()
       .handleAll[SchemeRejection] { rejections ⇒
         val schemes = rejections.map(_.supported).mkString(", ")
-        complete(BadRequest, "Uri scheme not allowed, supported schemes: " + schemes)
+        complete((BadRequest, "Uri scheme not allowed, supported schemes: " + schemes))
       }
       .handleAll[MethodRejection] { rejections ⇒
         val (methods, names) = rejections.map(r ⇒ r.supported -> r.supported.name).unzip
-        complete(MethodNotAllowed, List(Allow(methods)), "HTTP method not allowed, supported methods: " + names.mkString(", "))
+        complete((MethodNotAllowed, List(Allow(methods)), "HTTP method not allowed, supported methods: " + names.mkString(", ")))
       }
       .handle {
         case AuthorizationFailedRejection ⇒
-          complete(Forbidden, "The supplied authentication is not authorized to access this resource")
+          complete((Forbidden, "The supplied authentication is not authorized to access this resource"))
       }
       .handle {
         case MalformedFormFieldRejection(name, msg, _) ⇒
-          complete(BadRequest, "The form field '" + name + "' was malformed:\n" + msg)
+          complete((BadRequest, "The form field '" + name + "' was malformed:\n" + msg))
       }
       .handle {
         case MalformedHeaderRejection(headerName, msg, _) ⇒
-          complete(BadRequest, s"The value of HTTP header '$headerName' was malformed:\n" + msg)
+          complete((BadRequest, s"The value of HTTP header '$headerName' was malformed:\n" + msg))
       }
       .handle {
         case MalformedQueryParamRejection(name, msg, _) ⇒
-          complete(BadRequest, "The query parameter '" + name + "' was malformed:\n" + msg)
+          complete((BadRequest, "The query parameter '" + name + "' was malformed:\n" + msg))
       }
       .handle {
         case MalformedRequestContentRejection(msg, _) ⇒
-          complete(BadRequest, "The request content was malformed:\n" + msg)
+          complete((BadRequest, "The request content was malformed:\n" + msg))
       }
       .handle {
         case MissingCookieRejection(cookieName) ⇒
-          complete(BadRequest, "Request is missing required cookie '" + cookieName + '\'')
+          complete((BadRequest, "Request is missing required cookie '" + cookieName + '\''))
       }
       .handle {
         case MissingFormFieldRejection(fieldName) ⇒
-          complete(BadRequest, "Request is missing required form field '" + fieldName + '\'')
+          complete((BadRequest, "Request is missing required form field '" + fieldName + '\''))
       }
       .handle {
         case MissingHeaderRejection(headerName) ⇒
-          complete(BadRequest, "Request is missing required HTTP header '" + headerName + '\'')
+          complete((BadRequest, "Request is missing required HTTP header '" + headerName + '\''))
       }
       .handle {
         case MissingQueryParamRejection(paramName) ⇒
-          complete(NotFound, "Request is missing required query parameter '" + paramName + '\'')
+          complete((NotFound, "Request is missing required query parameter '" + paramName + '\''))
       }
       .handle {
         case RequestEntityExpectedRejection ⇒
-          complete(BadRequest, "Request entity expected but not supplied")
+          complete((BadRequest, "Request entity expected but not supplied"))
       }
       .handle {
         case TooManyRangesRejection(_) ⇒
-          complete(RequestedRangeNotSatisfiable, "Request contains too many ranges.")
+          complete((RequestedRangeNotSatisfiable, "Request contains too many ranges."))
       }
       .handle {
         case UnsatisfiableRangeRejection(unsatisfiableRanges, actualEntityLength) ⇒
-          complete(RequestedRangeNotSatisfiable, List(`Content-Range`(ContentRange.Unsatisfiable(actualEntityLength))),
-            unsatisfiableRanges.mkString("None of the following requested Ranges were satisfiable:\n", "\n", ""))
+          complete((RequestedRangeNotSatisfiable, List(`Content-Range`(ContentRange.Unsatisfiable(actualEntityLength))),
+            unsatisfiableRanges.mkString("None of the following requested Ranges were satisfiable:\n", "\n", "")))
       }
       .handleAll[AuthenticationFailedRejection] { rejections ⇒
         val rejectionMessage = rejections.head.cause match {
@@ -184,36 +184,36 @@ object RejectionHandler {
         // See https://code.google.com/p/chromium/issues/detail?id=103220
         // and https://bugzilla.mozilla.org/show_bug.cgi?id=669675
         val authenticateHeaders = rejections.map(r ⇒ `WWW-Authenticate`(r.challenge))
-        complete(Unauthorized, authenticateHeaders, rejectionMessage)
+        complete((Unauthorized, authenticateHeaders, rejectionMessage))
       }
       .handleAll[UnacceptedResponseContentTypeRejection] { rejections ⇒
         val supported = rejections.flatMap(_.supported)
-        complete(NotAcceptable, "Resource representation is only available with these Content-Types:\n" +
-          supported.map(_.value).mkString("\n"))
+        complete((NotAcceptable, "Resource representation is only available with these Content-Types:\n" +
+          supported.map(_.value).mkString("\n")))
       }
       .handleAll[UnacceptedResponseEncodingRejection] { rejections ⇒
         val supported = rejections.flatMap(_.supported)
-        complete(NotAcceptable, "Resource representation is only available with these Content-Encodings:\n" +
-          supported.map(_.value).mkString("\n"))
+        complete((NotAcceptable, "Resource representation is only available with these Content-Encodings:\n" +
+          supported.map(_.value).mkString("\n")))
       }
       .handleAll[UnsupportedRequestContentTypeRejection] { rejections ⇒
         val supported = rejections.flatMap(_.supported).mkString(" or ")
-        complete(UnsupportedMediaType, "The request's Content-Type is not supported. Expected:\n" + supported)
+        complete((UnsupportedMediaType, "The request's Content-Type is not supported. Expected:\n" + supported))
       }
       .handleAll[UnsupportedRequestEncodingRejection] { rejections ⇒
         val supported = rejections.map(_.supported.value).mkString(" or ")
-        complete(BadRequest, "The request's Content-Encoding is not supported. Expected:\n" + supported)
+        complete((BadRequest, "The request's Content-Encoding is not supported. Expected:\n" + supported))
       }
-      .handle { case ExpectedWebsocketRequestRejection ⇒ complete(BadRequest, "Expected Websocket Upgrade request") }
+      .handle { case ExpectedWebsocketRequestRejection ⇒ complete((BadRequest, "Expected Websocket Upgrade request")) }
       .handleAll[UnsupportedWebsocketSubprotocolRejection] { rejections ⇒
         val supported = rejections.map(_.supportedProtocol)
         complete(HttpResponse(BadRequest,
           entity = s"None of the websocket subprotocols offered in the request are supported. Supported are ${supported.map("'" + _ + "'").mkString(",")}.",
           headers = `Sec-WebSocket-Protocol`(supported) :: Nil))
       }
-      .handle { case ValidationRejection(msg, _) ⇒ complete(BadRequest, msg) }
+      .handle { case ValidationRejection(msg, _) ⇒ complete((BadRequest, msg)) }
       .handle { case x ⇒ sys.error("Unhandled rejection: " + x) }
-      .handleNotFound { complete(NotFound, "The requested resource could not be found.") }
+      .handleNotFound { complete((NotFound, "The requested resource could not be found.")) }
       .result()
 
   /**
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/MiscDirectives.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/MiscDirectives.scala
index 3262d34b08..bfdd1ef7e7 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/MiscDirectives.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/MiscDirectives.scala
@@ -16,7 +16,7 @@ trait MiscDirectives {
    * If the condition fails the route is rejected with a [[ValidationRejection]].
    */
   def validate(check: ⇒ Boolean, errorMsg: String): Directive0 =
-    Directive { inner ⇒ if (check) inner() else reject(ValidationRejection(errorMsg)) }
+    Directive { inner ⇒ if (check) inner(()) else reject(ValidationRejection(errorMsg)) }
 
   /**
    * Extracts the client's IP from either the X-Forwarded-For, Remote-Address or X-Real-IP header
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/RangeDirectives.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/RangeDirectives.scala
index 09bca74261..9901ceccf9 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/RangeDirectives.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/RangeDirectives.scala
@@ -108,7 +108,7 @@ trait RangeDirectives {
                     case Nil                   ⇒ ctx.reject(UnsatisfiableRangeRejection(ranges, length))
                     case Seq(satisfiableRange) ⇒ ctx.complete(rangeResponse(satisfiableRange, entity, length, headers))
                     case satisfiableRanges ⇒
-                      ctx.complete(PartialContent, headers, multipartRanges(satisfiableRanges, entity))
+                      ctx.complete((PartialContent, headers, multipartRanges(satisfiableRanges, entity)))
                   }
                 case None ⇒
                   // Ranges not supported for Chunked or CloseDelimited responses
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/SecurityDirectives.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/SecurityDirectives.scala
index ab3b625e66..95e4058167 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/SecurityDirectives.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/SecurityDirectives.scala
@@ -38,7 +38,7 @@ trait SecurityDirectives {
    * Extracts the potentially present [[HttpCredentials]] provided with the request's [[Authorization]] header.
    */
   def extractCredentials: Directive1[Option[HttpCredentials]] =
-    optionalHeaderValueByType[Authorization]().map(_.map(_.credentials))
+    optionalHeaderValueByType[Authorization](()).map(_.map(_.credentials))
 
   /**
    * Wraps the inner route with Http Basic authentication support using a given ``Authenticator[T]``.
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/WebsocketDirectives.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/WebsocketDirectives.scala
index a2fb8a2688..5768c4ea25 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/directives/WebsocketDirectives.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/directives/WebsocketDirectives.scala
@@ -19,7 +19,7 @@ trait WebsocketDirectives {
    * Extract the [[UpgradeToWebsocket]] header if existent. Rejects with an [[ExpectedWebsocketRequestRejection]], otherwise.
    */
   def extractUpgradeToWebsocket: Directive1[UpgradeToWebsocket] =
-    optionalHeaderValueByType[UpgradeToWebsocket]().flatMap {
+    optionalHeaderValueByType[UpgradeToWebsocket](()).flatMap {
       case Some(upgrade) ⇒ provide(upgrade)
       case None          ⇒ reject(ExpectedWebsocketRequestRejection)
     }
diff --git a/akka-http/src/main/scala/akka/http/scaladsl/server/util/ClassMagnet.scala b/akka-http/src/main/scala/akka/http/scaladsl/server/util/ClassMagnet.scala
index ec53ec0fd8..919dd2b6b6 100644
--- a/akka-http/src/main/scala/akka/http/scaladsl/server/util/ClassMagnet.scala
+++ b/akka-http/src/main/scala/akka/http/scaladsl/server/util/ClassMagnet.scala
@@ -18,9 +18,10 @@ trait ClassMagnet[T] {
   def extractPF: PartialFunction[Any, T]
 }
 object ClassMagnet {
-  implicit def apply[T](c: Class[T]): ClassMagnet[T] = ClassMagnet()(ClassTag(c))
+  implicit def fromClass[T](c: Class[T]): ClassMagnet[T] = ClassMagnet(ClassTag(c))
+  implicit def fromUnit[T](u: Unit)(implicit tag: ClassTag[T]) = ClassMagnet(tag)
 
-  implicit def apply[T](u: Unit)(implicit tag: ClassTag[T]): ClassMagnet[T] =
+  def apply[T](implicit tag: ClassTag[T]): ClassMagnet[T] =
     new ClassMagnet[T] {
       val classTag: ClassTag[T] = tag
       val runtimeClass: Class[T] = tag.runtimeClass.asInstanceOf[Class[T]]
diff --git a/akka-stream-testkit/src/test/scala/akka/stream/testkit/ScriptedTest.scala b/akka-stream-testkit/src/test/scala/akka/stream/testkit/ScriptedTest.scala
index 3ee8f3c637..54fe63dc9f 100644
--- a/akka-stream-testkit/src/test/scala/akka/stream/testkit/ScriptedTest.scala
+++ b/akka-stream-testkit/src/test/scala/akka/stream/testkit/ScriptedTest.scala
@@ -34,35 +34,40 @@ trait ScriptedTest extends Matchers {
         jumps ++= Vector.fill(ins.size - 1)(0) ++ Vector(outs.size)
       }
 
-      Script(providedInputs, expectedOutputs, jumps, inputCursor = 0, outputCursor = 0, outputEndCursor = 0, completed = false)
+      new Script(providedInputs, expectedOutputs, jumps, inputCursor = 0, outputCursor = 0, outputEndCursor = 0, completed = false)
     }
   }
 
-  final case class Script[In, Out](
-    providedInputs: Vector[In],
-    expectedOutputs: Vector[Out],
-    jumps: Vector[Int],
-    inputCursor: Int,
-    outputCursor: Int,
-    outputEndCursor: Int,
-    completed: Boolean) {
+  final class Script[In, Out](
+    val providedInputs: Vector[In],
+    val expectedOutputs: Vector[Out],
+    val jumps: Vector[Int],
+    val inputCursor: Int,
+    val outputCursor: Int,
+    val outputEndCursor: Int,
+    val completed: Boolean) {
     require(jumps.size == providedInputs.size)
 
     def provideInput: (In, Script[In, Out]) =
       if (noInsPending)
         throw new ScriptException("Script cannot provide more input.")
       else
-        (providedInputs(inputCursor), this.copy(inputCursor = inputCursor + 1, outputEndCursor = outputEndCursor + jumps(inputCursor)))
+        (providedInputs(inputCursor),
+          new Script(providedInputs, expectedOutputs, jumps, inputCursor = inputCursor + 1,
+            outputCursor, outputEndCursor = outputEndCursor + jumps(inputCursor), completed))
 
     def consumeOutput(out: Out): Script[In, Out] = {
       if (noOutsPending)
         throw new ScriptException(s"Tried to produce element ${out} but no elements should be produced right now.")
       out should be(expectedOutputs(outputCursor))
-      this.copy(outputCursor = outputCursor + 1)
+      new Script(providedInputs, expectedOutputs, jumps, inputCursor,
+        outputCursor = outputCursor + 1, outputEndCursor, completed)
     }
 
     def complete(): Script[In, Out] = {
-      if (finished) copy(completed = true)
+      if (finished)
+        new Script(providedInputs, expectedOutputs, jumps, inputCursor,
+          outputCursor = outputCursor + 1, outputEndCursor, completed = true)
       else fail("received onComplete prematurely")
     }
 
diff --git a/akka-stream-testkit/src/test/scala/akka/stream/testkit/TestUtils.scala b/akka-stream-testkit/src/test/scala/akka/stream/testkit/TestUtils.scala
index 85b3b5d4f2..b052280203 100644
--- a/akka-stream-testkit/src/test/scala/akka/stream/testkit/TestUtils.scala
+++ b/akka-stream-testkit/src/test/scala/akka/stream/testkit/TestUtils.scala
@@ -8,14 +8,24 @@ import java.nio.channels.DatagramChannel
 import java.nio.channels.ServerSocketChannel
 import java.net.InetSocketAddress
 import java.net.SocketAddress
+import java.net.DatagramSocket
+import java.net.ServerSocket
 
 object TestUtils { // FIXME: remove once going back to project dependencies
-  import scala.language.reflectiveCalls
-  // Structural type needed since DatagramSocket and ServerSocket has no common ancestor apart from Object
-  type GeneralSocket = {
+  trait GeneralSocket extends Any {
     def bind(sa: SocketAddress): Unit
     def close(): Unit
-    def getLocalPort(): Int
+    def getLocalPort: Int
+  }
+  implicit class GeneralDatagramSocket(val s: DatagramSocket) extends GeneralSocket {
+    def bind(sa: SocketAddress): Unit = s.bind(sa)
+    def close(): Unit = s.close()
+    def getLocalPort: Int = s.getLocalPort
+  }
+  implicit class GeneralServerSocket(val s: ServerSocket) extends GeneralSocket {
+    def bind(sa: SocketAddress): Unit = s.bind(sa)
+    def close(): Unit = s.close()
+    def getLocalPort: Int = s.getLocalPort
   }
 
   def temporaryServerAddress(address: String = "127.0.0.1", udp: Boolean = false): InetSocketAddress =
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/SinkTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/SinkTest.java
index 3272808283..cf7a6c76a9 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/SinkTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/SinkTest.java
@@ -82,7 +82,7 @@ public class SinkTest extends StreamTest {
     final Sink<Integer, ?> sink1 = Sink.actorRef(probe1.getRef(), "done1");
     final Sink<Integer, ?> sink2 = Sink.actorRef(probe2.getRef(), "done2");
 
-    final Sink<Integer, ?> sink = Sink.combine(sink1, sink2, new ArrayList(),
+    final Sink<Integer, ?> sink = Sink.combine(sink1, sink2, new ArrayList<Sink<Integer, ?>>(),
             new Function<Integer, Graph<UniformFanOutShape<Integer, Integer>, BoxedUnit>>() {
               public Graph<UniformFanOutShape<Integer, Integer>, BoxedUnit> apply(Integer elem) {
                 return Broadcast.create(elem);
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
index 426c154a38..2fc6a29cd3 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
@@ -566,7 +566,7 @@ public class SourceTest extends StreamTest {
     final Source<Integer, ?> source1 = Source.from(Arrays.asList(0, 1));
     final Source<Integer, ?> source2 = Source.from(Arrays.asList(2, 3));
 
-    final Source<Integer, ?> source = Source.combine(source1, source2, new ArrayList(),
+    final Source<Integer, ?> source = Source.combine(source1, source2, new ArrayList<Source<Integer, ?>>(),
             new Function<Integer, Graph<UniformFanInShape<Integer, Integer>, BoxedUnit>>() {
               public Graph<UniformFanInShape<Integer, Integer>, BoxedUnit> apply(Integer elem) {
                 return Merge.create(elem);
diff --git a/akka-stream-tests/src/test/scala/akka/stream/DslFactoriesConsistencySpec.scala b/akka-stream-tests/src/test/scala/akka/stream/DslFactoriesConsistencySpec.scala
index 492093a703..b484ce8fdf 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/DslFactoriesConsistencySpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/DslFactoriesConsistencySpec.scala
@@ -183,6 +183,7 @@ class DslFactoriesConsistencySpec extends WordSpec with Matchers {
   def returnTypeString(m: Method): String =
     m.returnType.getName.drop("akka.stream.".length)
 
+  import language.existentials
   case class Method(name: String, parameterTypes: List[Class[_]], returnType: Class[_], declaringClass: Class[_])
 
   sealed trait MatchResult {
diff --git a/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala
index e2e33dc720..63793cbd21 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/io/TcpSpec.scala
@@ -505,7 +505,7 @@ class TcpSpec extends AkkaSpec("akka.io.tcp.windows-connection-abort-workaround-
       val address = temporaryServerAddress()
       val firstClientConnected = Promise[Unit]()
       val takeTwoAndDropSecond = Flow[IncomingConnection].map(conn ⇒ {
-        firstClientConnected.trySuccess()
+        firstClientConnected.trySuccess(())
         conn
       }).grouped(2).take(1).map(_.head)
       Tcp().bind(address.getHostName, address.getPort)
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphStageTimersSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphStageTimersSpec.scala
index 5fb20ff96c..63dc6b198a 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphStageTimersSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphStageTimersSpec.scala
@@ -90,12 +90,12 @@ class GraphStageTimersSpec extends AkkaSpec {
     "receive single-shot timer" in {
       val driver = setupIsolatedStage
 
-      within(2 seconds) {
-        within(500 millis, 1 second) {
+      within(2.seconds) {
+        within(500.millis, 1.second) {
           driver ! TestSingleTimer
           expectMsg(Tick(1))
         }
-        expectNoMsg(1 second)
+        expectNoMsg(1.second)
       }
 
       driver.stopStage()
@@ -104,15 +104,15 @@ class GraphStageTimersSpec extends AkkaSpec {
     "resubmit single-shot timer" in {
       val driver = setupIsolatedStage
 
-      within(2.5 seconds) {
-        within(500 millis, 1 second) {
+      within(2.5.seconds) {
+        within(500.millis, 1.second) {
           driver ! TestSingleTimerResubmit
           expectMsg(Tick(1))
         }
-        within(1 second) {
+        within(1.second) {
           expectMsg(Tick(2))
         }
-        expectNoMsg(1 second)
+        expectNoMsg(1.second)
       }
 
       driver.stopStage()
@@ -122,13 +122,13 @@ class GraphStageTimersSpec extends AkkaSpec {
       val driver = setupIsolatedStage
 
       driver ! TestCancelTimer
-      within(500 millis) {
+      within(500.millis) {
         expectMsg(TestCancelTimerAck)
       }
-      within(300 millis, 1 second) {
+      within(300.millis, 1.second) {
         expectMsg(Tick(1))
       }
-      expectNoMsg(1 second)
+      expectNoMsg(1.second)
 
       driver.stopStage()
     }
@@ -137,11 +137,11 @@ class GraphStageTimersSpec extends AkkaSpec {
       val driver = setupIsolatedStage
 
       driver ! TestRepeatedTimer
-      val seq = receiveWhile(2 seconds) {
+      val seq = receiveWhile(2.seconds) {
         case t: Tick ⇒ t
       }
       seq should have length 5
-      expectNoMsg(1 second)
+      expectNoMsg(1.second)
 
       driver.stopStage()
     }
diff --git a/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala b/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala
index 8e2596d891..25a436b083 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/ActorMaterializerImpl.scala
@@ -339,7 +339,6 @@ private[akka] object ActorProcessorFactory {
       case Scan(z, f, _)              ⇒ interp(fusing.Scan(z, f, settings.supervisionDecider))
       case Fold(z, f, _)              ⇒ interp(fusing.Fold(z, f, settings.supervisionDecider))
       case Recover(pf, _)             ⇒ interp(fusing.Recover(pf))
-      case Scan(z, f, _)              ⇒ interp(fusing.Scan(z, f, settings.supervisionDecider))
       case Expand(s, f, _)            ⇒ interp(fusing.Expand(s, f))
       case Conflate(s, f, _)          ⇒ interp(fusing.Conflate(s, f, settings.supervisionDecider))
       case Buffer(n, s, _)            ⇒ interp(fusing.Buffer(n, s))
diff --git a/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala b/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala
index a513baed8d..329e73c0d6 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/ActorProcessor.scala
@@ -114,7 +114,7 @@ private[akka] abstract class BatchingInputBuffer(val size: Int, val pump: Pump)
   }
 
   protected def onSubscribe(subscription: Subscription): Unit = {
-    assert(subscription != null)
+    require(subscription != null)
     if (upstreamCompleted) subscription.cancel()
     else {
       upstream = subscription
diff --git a/akka-stream/src/main/scala/akka/stream/impl/FanIn.scala b/akka-stream/src/main/scala/akka/stream/impl/FanIn.scala
index 54f0c6c4b9..5953638069 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/FanIn.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/FanIn.scala
@@ -166,7 +166,7 @@ private[akka] object FanIn {
       while (!(marked(id) && pending(id))) {
         id += 1
         if (id == inputCount) id = 0
-        assert(id != preferredId, "Tried to dequeue without waiting for any input")
+        require(id != preferredId, "Tried to dequeue without waiting for any input")
       }
       id
     }
diff --git a/akka-stream/src/main/scala/akka/stream/impl/FanOut.scala b/akka-stream/src/main/scala/akka/stream/impl/FanOut.scala
index 6791d26854..4417511937 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/FanOut.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/FanOut.scala
@@ -141,7 +141,7 @@ private[akka] object FanOut {
       while (!(marked(id) && pending(id))) {
         id += 1
         if (id == outputCount) id = 0
-        assert(id != preferredId, "Tried to enqueue without waiting for any demand")
+        require(id != preferredId, "Tried to enqueue without waiting for any demand")
       }
       id
     }
diff --git a/akka-stream/src/main/scala/akka/stream/impl/fusing/ActorInterpreter.scala b/akka-stream/src/main/scala/akka/stream/impl/fusing/ActorInterpreter.scala
index 76e9fdb77b..c9bb2373e7 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/fusing/ActorInterpreter.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/fusing/ActorInterpreter.scala
@@ -44,7 +44,7 @@ private[akka] class BatchingActorInputBoundary(val size: Int, val name: String)
 
   private def dequeue(): Any = {
     val elem = inputBuffer(nextInputElementCursor)
-    assert(elem ne null)
+    require(elem ne null)
     inputBuffer(nextInputElementCursor) = null
 
     batchRemaining -= 1
@@ -110,7 +110,7 @@ private[akka] class BatchingActorInputBoundary(val size: Int, val name: String)
     }
 
   private def onSubscribe(subscription: Subscription): Unit = {
-    assert(subscription != null)
+    require(subscription != null)
     if (upstreamCompleted)
       tryCancel(subscription)
     else if (downstreamCanceled) {
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
index 720d970daf..39354c3b20 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
@@ -319,7 +319,7 @@ object Flow extends FlowApply {
  * Flow with attached input and output, can be executed.
  */
 case class RunnableGraph[+Mat](private[stream] val module: StreamLayout.Module) extends Graph[ClosedShape, Mat] {
-  assert(module.isRunnable)
+  require(module.isRunnable)
   def shape = ClosedShape
 
   /**