diff --git a/matrix/server.py b/matrix/server.py
index 9fce1c2..d1becdb 100644
--- a/matrix/server.py
+++ b/matrix/server.py
@@ -1618,6 +1618,8 @@ class MatrixServer(object):
 
         if isinstance(response, ErrorResponse):
             self.handle_error_response(response)
+            room_buffer = self.room_buffers[response.room_id]
+            room_buffer.backlog_pending = False
 
         elif isinstance(response, ToDeviceResponse):
             try: