After furthing testing, I removed django_postgrespool (DATABASES['default']['ENGINE'] = 'django_postgrespool') and the error was finally more explicit about an integrity error. I was able to fix it and the error was gone.
Why the error is not the actual error when using django_postgrespool? Thanks -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/da184a09-5890-48a5-8bfb-d67c4df36540%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.

