diff --git a/swh/scheduler/backend.py b/swh/scheduler/backend.py
--- a/swh/scheduler/backend.py
+++ b/swh/scheduler/backend.py
@@ -61,6 +61,10 @@
             return self._db
         return BaseDb.from_pool(self._pool)
 
+    def put_db(self, db):
+        if db is not self._db:
+            db.put_conn()
+
     task_type_keys = [
         'type', 'description', 'backend_name', 'default_interval',
         'min_interval', 'max_interval', 'backoff_factor', 'max_queue_length',
diff --git a/swh/scheduler/updater/backend.py b/swh/scheduler/updater/backend.py
--- a/swh/scheduler/updater/backend.py
+++ b/swh/scheduler/updater/backend.py
@@ -40,6 +40,10 @@
             return self._db
         return BaseDb.from_pool(self._pool)
 
+    def put_db(self, db):
+        if db is not self._db:
+            db.put_conn()
+
     cache_put_keys = ['url', 'cnt', 'last_seen', 'origin_type']
 
     @db_transaction()