[1.7.x] Fixed #23451 -- Fixed typo in inlineformset_factory() error message.

Backport of f7eee04ebe from master

django/forms/models.py

@@ -950,7 +950,7 @@ def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):
                     (fk.rel.to != parent_model and
                      fk.rel.to not in parent_model._meta.get_parent_list()):
                 raise ValueError(
-                    "fk_name '%s' is not a ForeignKey to '%s.%'."
+                    "fk_name '%s' is not a ForeignKey to '%s.%s'."
                     % (fk_name, parent_model._meta.app_label, parent_model._meta.object_name))
         elif len(fks_to_parent) == 0:
             raise ValueError(

docs/releases/1.7.1.txt

@@ -23,3 +23,6 @@ Bugfixes
 
 * The ``@deconstructible`` decorator now fails with a ``ValueError`` if the
   decorated object cannot automatically be imported (:ticket:`23418`).
+
+* Fixed a typo in an ``inlineformset_factory()`` error message that caused a
+  crash (:ticket:`23451`).

tests/model_formsets/tests.py

@@ -805,6 +805,12 @@ class ModelFormsetTest(TestCase):
         formset = AuthorBooksFormSet(data, instance=author, queryset=custom_qs)
         self.assertTrue(formset.is_valid())
 
+    def test_inline_formsets_with_wrong_fk_name(self):
+        """ Regression for #23451 """
+        message = "fk_name 'title' is not a ForeignKey to 'model_formsets.Author'."
+        with self.assertRaisesMessage(ValueError, message):
+            inlineformset_factory(Author, Book, fields="__all__", fk_name='title')
+
     def test_custom_pk(self):
         # We need to ensure that it is displayed