diff --git a/src/Client/MultiplexedConnections.cpp b/src/Client/MultiplexedConnections.cpp
index c4c5010df342..3b1a09631dd9 100644
--- a/src/Client/MultiplexedConnections.cpp
+++ b/src/Client/MultiplexedConnections.cpp
@@ -232,7 +232,7 @@ void MultiplexedConnections::sendIgnoredPartUUIDs(const std::vector<UUID> & uuid
 void MultiplexedConnections::sendClusterFunctionReadTaskResponse(const ClusterFunctionReadTaskResponse & response)
 {
     std::lock_guard lock(cancel_mutex);
-    if (cancelled)
+    if (cancelled || !current_connection || !current_connection->isConnected())
         return;
     current_connection->sendClusterFunctionReadTaskResponse(response);
 }
@@ -241,7 +241,7 @@ void MultiplexedConnections::sendClusterFunctionReadTaskResponse(const ClusterFu
 void MultiplexedConnections::sendMergeTreeReadTaskResponse(const ParallelReadResponse & response)
 {
     std::lock_guard lock(cancel_mutex);
-    if (cancelled)
+    if (cancelled || !current_connection || !current_connection->isConnected())
         return;
     current_connection->sendMergeTreeReadTaskResponse(response);
 }
@@ -527,9 +527,12 @@ MultiplexedConnections::ReplicaState & MultiplexedConnections::getReplicaForRead
 
 void MultiplexedConnections::invalidateReplica(ReplicaState & state)
 {
+    Connection * old_connection = state.connection;
     state.connection = nullptr;
     state.pool_entry = IConnectionPool::Entry();
     --active_connection_count;
+    if (current_connection == old_connection)
+        current_connection = nullptr;
 }
 
 void MultiplexedConnections::setAsyncCallback(AsyncCallback async_callback)