foo.diff

diff --git a/django/forms/models.py b/django/forms/models.py
index 31e4bba..8a70baa 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -391,7 +391,13 @@ class BaseModelForm(BaseForm):
         # Override any validation error messages defined at the model level
         # with those defined at the form level.
         opts = self._meta
-        for field, messages in errors.error_dict.items():
+
+        if hasattr(errors, 'error_dict'):
+            error_dict = errors.error_dict
+        else:
+            error_dict = {NON_FIELD_ERRORS: errors}
+
+        for field, messages in error_dict.items():
             if (field == NON_FIELD_ERRORS and opts.error_messages and
                     NON_FIELD_ERRORS in opts.error_messages):
                 error_messages = opts.error_messages[NON_FIELD_ERRORS]
@@ -423,8 +429,10 @@ class BaseModelForm(BaseForm):
             if isinstance(field, InlineForeignKeyField):
                 exclude.append(name)
 
-        # Update the model instance with self.cleaned_data.
-        self.instance = construct_instance(self, self.instance, opts.fields, exclude)
+        try:
+            self.instance = construct_instance(self, self.instance, opts.fields, exclude)
+        except ValidationError as e:
+            self._update_errors(e)
 
         try:
             self.instance.full_clean(exclude=exclude, validate_unique=False)