[5.2.x] Fixed #36120 -- Raised FieldError when targeting a composite primary key field with QuerySet.update().

Backport of 72ff18d41cfb004ae180bdf87fd8bad93041c691 from main.

1 files changed, 4 insertions, 0 deletions

diff --git a/django/db/models/sql/subqueries.py b/django/db/models/sql/subqueries.py
index b2810c8413..9cb971b38f 100644
--- a/django/db/models/sql/subqueries.py
+++ b/django/db/models/sql/subqueries.py
@@ -90,6 +90,10 @@ class UpdateQuery(Query):
                 not (field.auto_created and not field.concrete) or not field.concrete
             )
             model = field.model._meta.concrete_model
+            if field.name == "pk" and model._meta.is_composite_pk:
+                raise FieldError(
+                    "Composite primary key fields must be updated individually."
+                )
             if not direct or (field.is_relation and field.many_to_many):
                 raise FieldError(
                     "Cannot update model field %r (only non-relations and "