Fixed #31148 -- Added error messages on update()/delete() operations following union(), intersection(), and difference().

django/db/models/query.py

@@ -711,6 +711,7 @@ class QuerySet:
 
     def delete(self):
         """Delete the records in the current QuerySet."""
+        self._not_support_combined_queries('delete')
         assert not self.query.is_sliced, \
             "Cannot use 'limit' or 'offset' with delete."
 
@@ -756,6 +757,7 @@ class QuerySet:
         Update all elements in the current QuerySet, setting all the given
         fields to the appropriate values.
         """
+        self._not_support_combined_queries('update')
         assert not self.query.is_sliced, \
             "Cannot update a query once a slice has been taken."
         self._for_write = True