The error is caused by the user.user_info.save() line has thrown an error, and the transaction has been flagged as broken (PostgreSQL enforces rolling back the whole transaction or to any savepoint stored before doing any more queries in the transaction).
You can rollback the transaction when an error occurs like so:
from django.db import IntegrityError, transaction @receiver(post_save, sender=User) def saveUserAndInfo(sender, instance, **kwargs): user = instance try: with transaction.atomic(): user.user_info.save() except IntegrityError: info = UserInfo() info.user = user info.save() This is greatly described in the documentation.
Also, note that catching all exception types is not generally the best idea as you might silence exceptions you weren't expecting.