1 files changed, 11 insertions, 2 deletions
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index e451d6dc86..8ddded8389 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -45,7 +45,7 @@ from synapse.events.validator import EventValidator
 from synapse.logging.context import run_in_background
 from synapse.metrics.background_process_metrics import run_as_background_process
 from synapse.replication.http.send_event import ReplicationSendEventRestServlet
-from synapse.storage.data_stores.main.events_worker import EventRedactBehaviour
+from synapse.storage.databases.main.events_worker import EventRedactBehaviour
 from synapse.storage.state import StateFilter
 from synapse.types import (
     Collection,
@@ -768,6 +768,15 @@ class EventCreationHandler(object):
         else:
             prev_event_ids = await self.store.get_prev_events_for_room(builder.room_id)
 
+        # we now ought to have some prev_events (unless it's a create event).
+        #
+        # do a quick sanity check here, rather than waiting until we've created the
+        # event and then try to auth it (which fails with a somewhat confusing "No
+        # create event in auth events")
+        assert (
+            builder.type == EventTypes.Create or len(prev_event_ids) > 0
+        ), "Attempting to create an event with no prev_events"
+
         event = await builder.build(prev_event_ids=prev_event_ids)
         context = await self.state.compute_event_context(event)
         if requester:
@@ -1061,7 +1070,7 @@ class EventCreationHandler(object):
                     raise SynapseError(400, "Cannot redact event from a different room")
 
             prev_state_ids = await context.get_prev_state_ids()
-            auth_events_ids = await self.auth.compute_auth_events(
+            auth_events_ids = self.auth.compute_auth_events(
                 event, prev_state_ids, for_verification=True
             )
             auth_events = await self.store.get_events(auth_events_ids)