Fixed #25292 -- Fixed crash in ManyToManyField.through_fields check.

1 files changed, 4 insertions, 0 deletions

diff --git a/django/db/models/base.py b/django/db/models/base.py
index 2444c22b01..80d98b1399 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -1687,6 +1687,10 @@ class Model(six.with_metaclass(ModelBase)):
                 )
 
         for f in cls._meta.local_many_to_many:
+            # Skip nonexistent models.
+            if isinstance(f.remote_field.through, six.string_types):
+                continue
+
             # Check if auto-generated name for the M2M field is too long
             # for the database.
             for m2m in f.remote_field.through._meta.local_fields: