[Fixed]-Django Reverse for 'messages_inbox' with arguments '()' and keyword arguments '{}' not found. 0 pattern(s) tried: []

You’re including the djangobb_forum urls with a namespace, and since your django_messages urls are themselves included within the other, you need the namespace there too.

<a href="{% url 'djangobb:messages_inbox' %}">

I’m not sure that’s what you meant to do though; you should probably include the django_messages urls directly into the main urls.py.