Troubleshooting issues with Admin Interface
- IntelliSearch returning no results. Icon won't stop spinning
- Affiliates can't be assigned from Order page
- All modals are empty and never stop loading
The issue is caused by Display Errors set to On in your PHP configuration. We are going to explain it with an example but keep in mind that it's a bit complicated. You can skip this part if you want to jump to solution.
Let's focus on the IntelliSearch of WHMCS. When you press enter to start the search, WHMCS submits your request to self page. The page then responds with a partially loaded output caused by a PHP notice or warning that leads to an Error 500. WHMCS has no fallbacks to deal with a partially loaded page therefore live search and modals stop working without any notice.
In order to solve the issue you should turn off Display Errors from Plesk, cPanel or webserver in general. This option should always be disabled in production environments not only because it can cause you the problem we have just described but also because it's a security risk.