'NoneType' object has no attribute '_inc_path'

Remember to add the following line of code in models.py so that to enable user to post on wagtail  Blog_Homepage:

```
from django.contrib.auth.models import User

```

it  will solve the following error in wagtail cms:

```
AttributeError at /cms/pages/add/blog/blogpage/3/
'NoneType' object has no attribute '_inc_path'

```

May Almighty God , guide you. Amen