On the last couple of EE upgrades I've received a PHP error regarding MB_ENABLED:
A PHP Error was encountered Severity: Notice
Message: Use of undefined constant MB_ENABLED - assumed 'MB_ENABLED'
Line Number: 367
This is repeated for each instance of
MB_ENABLED in the system/codeigniter/system/libraries/Encrypt.php file.
If I wrap each instance of
MB_ENABLED in single quotes then it resolves the issue but having to do this on each upgrade is a little annoying.
It seems to be mentioned on the EllisLab forums also but the solution is again to modify core files. Is this a bug? Has anyone encountered this issue in upgrading recently?