I had the same problem after an upgrade. After creating a case with support and a few days later we found out that theres a bug regarding Unicode at sysmgr login.
We were asked if only english characters were being used, we did. But we changed the password of the admin account anyway just to be sure (we had an : and . in the password). After the password change we managed to login. So try changing your password if you're having this issue.
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