diff --git a/actor/src/main/mima-filters/1.1.x.backwards.excludes/backoff-calculation.excludes b/actor/src/main/mima-filters/2.0.x.backwards.excludes/backoff-calculation.excludes
similarity index 82%
rename from actor/src/main/mima-filters/1.1.x.backwards.excludes/backoff-calculation.excludes
rename to actor/src/main/mima-filters/2.0.x.backwards.excludes/backoff-calculation.excludes
index 8a700c471d..e3f26f252c 100644
--- a/actor/src/main/mima-filters/1.1.x.backwards.excludes/backoff-calculation.excludes
+++ b/actor/src/main/mima-filters/2.0.x.backwards.excludes/backoff-calculation.excludes
@@ -15,5 +15,7 @@
 # specific language governing permissions and limitations
 # under the License.
 
-# Move BackoffSupervisor.calculateDelay
+# Move BackoffSupervisor.calculateDelay to RetrySupport
+# Was removed in Pekko 1.2.0 but added back in 1.2.1 due to breakages
+# in pekko-persistence-cassandra - this method is deprecated in 1.2.1+
 ProblemFilters.exclude[DirectMissingMethodProblem]("org.apache.pekko.pattern.BackoffSupervisor.calculateDelay")
diff --git a/docs/src/main/paradox/release-notes/releases-1.2.md b/docs/src/main/paradox/release-notes/releases-1.2.md
index 8ea94d6a73..416d4f47ef 100644
--- a/docs/src/main/paradox/release-notes/releases-1.2.md
+++ b/docs/src/main/paradox/release-notes/releases-1.2.md
@@ -86,3 +86,9 @@ Most of the changes appeared in the milestone releases (1.2.0-M1 and 1.2.0-M2) b
 * slfj4 2.0.17
 * jupiter-junit 5.13.3
 * scala 2.12.20, 2.13.16, 3.3.6
+
+### Known Issues
+
+This release breaks binary compatibility for [pekko-persistence-cassandra](https://github.com/apache/pekko-persistence-cassandra/issues/305)
+and users of that lib will need to avoid Pekko 1.2.0 release. We will fix
+this in the 1.2.1 release.