diff --git a/changelog.d/17816.bugfix b/changelog.d/17816.bugfix
new file mode 100644
index 00000000000..5dd276709b0
--- /dev/null
+++ b/changelog.d/17816.bugfix
@@ -0,0 +1 @@
+Avoid lost data on some database query retries.
diff --git a/synapse/storage/databases/main/media_repository.py b/synapse/storage/databases/main/media_repository.py
index 7617fd3ad49..7a96e254321 100644
--- a/synapse/storage/databases/main/media_repository.py
+++ b/synapse/storage/databases/main/media_repository.py
@@ -729,10 +729,10 @@ def update_cache_txn(txn: LoggingTransaction) -> None:
 
             txn.execute_batch(
                 sql,
-                (
+                [
                     (time_ms, media_origin, media_id)
                     for media_origin, media_id in remote_media
-                ),
+                ],
             )
 
             sql = (
@@ -740,7 +740,7 @@ def update_cache_txn(txn: LoggingTransaction) -> None:
                 " WHERE media_id = ?"
             )
 
-            txn.execute_batch(sql, ((time_ms, media_id) for media_id in local_media))
+            txn.execute_batch(sql, [(time_ms, media_id) for media_id in local_media])
 
         await self.db_pool.runInteraction(
             "update_cached_last_access_time", update_cache_txn