Hello... Are you still using Postgre 9.4 as mentioned in other posts? Do you have the timeline to upgrade it soon? If so, to which version?
Django 3 supports only Postgre 9.5 and up. It would be nice if you could upgrade your Postgre to one of the latest versions like 11. Having the latest version would give us the most time for support. If you just upgraded it to the bare minimum version of 9.5, I'm afraid it would be out of support again in a short time.
Thank you.