I'm getting this error. Pretty sure its because we upgraded the server. Is there any possible fix for this? Its happening to some usergroups but not all.
Are you by any chance running PHP 5.4? MyBB doesn't fully support PHP 5.4 yet. These errors will be fixed in 1.6.10, however in the meantime you can disable the error messages in AdminCP -> Configuration -> Server and Optimization Options -> Use Error Handling -> Off
It does appear the PHP 5.4 is not supported by looking at the screen.s