Hi, we just had an issue signing in a particular wallet. First we were getting a 500 error from /server/users then we deleted the row effected at the backend and started to get a 400 error from /server/users. Only this single particular wallet seemed to be effected. Haveing been unable to determine a cause we have created a new server to continue development and have left the server which gave the error open so maybe it will give you some clues as to what went wrong.
The server with the problem was titled TestNet3