1 files changed, 4 insertions, 0 deletions
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index 0b3fe6cbf5..75c9e8355f 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -52,6 +52,7 @@ indicate which side is sending, these are *not* included on the wire::
 import fcntl
 import logging
 import struct
+import traceback
 from collections import defaultdict
 
 from six import iteritems, iterkeys
@@ -241,6 +242,7 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
     def send_error(self, error_string, *args):
         """Send an error to remote and close the connection.
         """
+        logger.error("[%s] Sending error: %s", self.id(), error_string % args)
         self.send_command(ErrorCommand(error_string % args))
         self.close()
 
@@ -323,6 +325,8 @@ class BaseReplicationStreamProtocol(LineOnlyReceiver):
         we or the remote has closed the connection)
         """
         logger.info("[%s] Stop producing", self.id())
+        # debug for #4733
+        logger.info("Traceback: %s", "".join(traceback.format_stack()))
         self.on_connection_closed()
 
     def connectionLost(self, reason):