Well, I was using an Login Authenthicator, so when you are premium, your UUIDS changes to the premium UUID. Then I wanted to use only Offline UUIDs even if you are premium, is there a way to fix now my account?
That happens only to my account, error logs: https://pastebin.com/z1nrqwkf

Just as a side note, doing that will make name changes of premium players no longer work.

So, Using Offline UUIDS on a Premium player will produce that error?

That too.

Oh, there isn't a way to prevent that? Or I need to use Online UUID to premium users?

If you want to allow name changes, the yes, absolutely.

Done, no problems right now. Thanks :P