"This account needs to be converted to a Battle.net Account"

Hello. This message just started popping up for me today whenever i try to log in with ANY account. I was playing normally yesterday.

I've tried:
-Checking the realmist.
- Clearing WTF folder.
- Clearing Cache.
-Resetting my router.
-Firewall.

None of these fixed my problem. Any one have any idea of how i can fix this?

Edit: Fixed. Problem was found on the config.wtf file. For some reason it had "SET install locale enUS", i simply deleted it and now i can play normally.

I am having the same problem. I tried that but no fix.