diff --git a/src/Ydb.Sdk/CHANGELOG.md b/src/Ydb.Sdk/CHANGELOG.md
index 4fbbcd8a..6445017e 100644
--- a/src/Ydb.Sdk/CHANGELOG.md
+++ b/src/Ydb.Sdk/CHANGELOG.md
@@ -1,3 +1,4 @@
+- Fixed bug Topic Reader: NullReferenceException when handling StopPartitionSessionRequest ([#528](https://github.com/ydb-platform/ydb-dotnet-sdk/issues/528)).
 - Feat ADO.NET: Added YSON type support (YdbDbType.Yson) with byte[] values.
 
 ## v0.23.0
diff --git a/src/Ydb.Sdk/src/Services/Topic/Reader/Reader.cs b/src/Ydb.Sdk/src/Services/Topic/Reader/Reader.cs
index eea1a7a1..3b7a294b 100644
--- a/src/Ydb.Sdk/src/Services/Topic/Reader/Reader.cs
+++ b/src/Ydb.Sdk/src/Services/Topic/Reader/Reader.cs
@@ -322,11 +322,11 @@ private async Task RunProcessingStreamResponse()
                     case ServerMessageOneofCase.CommitOffsetResponse:
                         HandleCommitOffsetResponse(messageFromServer.CommitOffsetResponse);
                         break;
-                    case ServerMessageOneofCase.PartitionSessionStatusResponse:
-                    case ServerMessageOneofCase.UpdateTokenResponse:
                     case ServerMessageOneofCase.StopPartitionSessionRequest:
                         await StopPartitionSessionRequest(messageFromServer.StopPartitionSessionRequest);
                         break;
+                    case ServerMessageOneofCase.PartitionSessionStatusResponse:
+                    case ServerMessageOneofCase.UpdateTokenResponse:
                     case ServerMessageOneofCase.InitResponse:
                     case ServerMessageOneofCase.None:
                     case ServerMessageOneofCase.UpdatePartitionSession: