Acknoweldeged a limitation of the parallel test runner.

Notably it will fail to report a Model.DoesNotExist exceptions because
the class itself isn't pickleable. (Django has specific code to make its
instances pickleable.)

1 files changed, 11 insertions, 0 deletions

diff --git a/docs/ref/django-admin.txt b/docs/ref/django-admin.txt
index a98b60b45f..0c88b5aadb 100644
--- a/docs/ref/django-admin.txt
+++ b/docs/ref/django-admin.txt
@@ -1285,6 +1285,17 @@ correctly:
 
     $ pip install tblib
 
+.. warning::
+
+    When test parallelization is enabled and a test fails, Django may be
+    unable to display the exception traceback. This can make debugging
+    difficult. If you encounter this problem, run the affected test without
+    parallelization to see the traceback of the failure.
+
+    This is a known limitation. It arises from the need to serialize objects
+    in order to exchange them between processes. See
+    :ref:`python:pickle-picklable` for details.
+
 testserver <fixture fixture ...>
 --------------------------------