diff --git a/django/contrib/sessions/tests.py b/django/contrib/sessions/tests.py
index e8aad0f05fd..9b669211db2 100644
--- a/django/contrib/sessions/tests.py
+++ b/django/contrib/sessions/tests.py
@@ -160,11 +160,16 @@ class SessionTestsMixin(object):
     def test_invalid_key(self):
         # Submitting an invalid session key (either by guessing, or if the db has
         # removed the key) results in a new key being generated.
-        session = self.backend('1')
-        session.save()
-        self.assertNotEqual(session.session_key, '1')
-        self.assertEqual(session.get('cat'), None)
-        session.delete()
+        try:
+            session = self.backend('1')
+            session.save()
+            self.assertNotEqual(session.session_key, '1')
+            self.assertEqual(session.get('cat'), None)
+            session.delete()
+        finally:
+            # Some backends leave a stale cache entry for the invalid
+            # session key; make sure that entry is manually deleted
+            session.delete('1')
 
     # Custom session expiry
     def test_default_expiry(self):