Thread:TempAcc00/@comment-46934204-20200919233902

what does this mean?

''We don't recognize these credentials. Your username may have been changed as a result of login system changes, adding -fduser or -gpuser as a suffix. Try again or register a new account.''

Honestly, I have had a long day, I just wanna chill and talk to my fandom friends, please just fix this bs or tell me how to fix it. 