I am using suitecrm 7.9.1
Whenever I create a record (in any module e.g. Contacts, Leads, Accounts etc) and click "Save" button to submit form then I get 500 error.
Other custom/default forms are working fine and this issue only occurring on production server.
make sure that you have proper .htaccess and permission on server should be 755. if that still doesn't resolve your issue then share Sugar and server error log.