Application issue

The application page is having problems when trying to apply e.g. http://barms.rh.strategiesuk.net/apply/?job_id=ba1455_1414508137

when trying to apply for the jobs a new page opens saying “Sorry, this file type is not allowed. Please go back and try again.”

This shows up even when no file is attached, I have a extension that shows me the redirect path, it saying it’s a 500 error.

Any help would be appreciated.

Thanks

https://ww.wp.xz.cn/plugins/wpbroadbean/