If i remember correctly, this is can be happened because of pincode system.
Open config/servers.php find string related to pincode system and turn it off.
This has nothing to do with pincode.
/lib/Flux/SessionData.php
if (!$loginAthenaGroup->isAuth($username, $password)) {
throw new Flux_LoginError('Invalid login', Flux_LoginError::INVALID_LOGIN);
}
Invalid Login error is usually given because users haven't changed the MD5 config in servers.php.
i have turned off the md5 on servers.php still same error