Fix rolling back when using workers (#11255)

Fixes #11252

1 files changed, 12 insertions, 11 deletions

diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index 1629d2a53c..b5c1c14ee3 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -133,22 +133,23 @@ def prepare_database(
 
             # if it's a worker app, refuse to upgrade the database, to avoid multiple
             # workers doing it at once.
-            if (
-                config.worker.worker_app is not None
-                and version_info.current_version != SCHEMA_VERSION
-            ):
+            if config.worker.worker_app is None:
+                _upgrade_existing_database(
+                    cur,
+                    version_info,
+                    database_engine,
+                    config,
+                    databases=databases,
+                )
+            elif version_info.current_version < SCHEMA_VERSION:
+                # If the DB is on an older version than we expect the we refuse
+                # to start the worker (as the main process needs to run first to
+                # update the schema).
                 raise UpgradeDatabaseException(
                     OUTDATED_SCHEMA_ON_WORKER_ERROR
                     % (SCHEMA_VERSION, version_info.current_version)
                 )
 
-            _upgrade_existing_database(
-                cur,
-                version_info,
-                database_engine,
-                config,
-                databases=databases,
-            )
         else:
             logger.info("%r: Initialising new database", databases)