Cornerstone plugin problem can't seems to get fixed

[Evedd]

Hello,
I encounter some fatal error with cornerstone in my X theme.
I’ve tried manually re-installing the plugin through ftp as you advised it in some post but it doesn’t seems to work. I still have the fatal error and wordpress telling me they are not going to activate it because of the fatal error…

[friech]

Hi @Evedd,

Thank you for writing in, please do the following first:

• Ensure that you are fully up to date. WordPress, Theme, and Cornerstone (Version Compatibility)

• Clear all the site caches (plugin, server-side, CDN, and browser’s cache) so that the code from the latest release is always in use. This will help you to avoid any potential errors. While you’re at it, please deactivate this caching feature while we tackle this issue.

• Test for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.

If the issue persists, please provide us login credentials on a “Secure Note” so we can take a closer look.

Cheers!