Cornerstone Plugin could not be activated because it triggered a fatal error

Plugin could not be activated because it triggered a fatal error.

Fatal error: Cannot declare class Cornerstone_Plugin_Base, because the name is already in use in /home/janit002/public_html/wp-content/plugins/cornerstone/includes/utility/plugin-base.php on line 6

Is it possible that pro editor replaces cornerstone?

I would say delete it and let it try to reinstall itself after visiting the overview page under the X/Pro settings page.

Hi there @tracyspr,

As you’re using Pro, you don’t need to install Cornerstone separately. Make sure Cornerstone is deactivated and deleted, then everything will work without an issue.


Hello, I have still the same issue .

Suddently the website crashed and now I can see only shortcodes.

I’m using PRO, Cornerstone is deleted from the server .

What can I do next?

Hello @alexander11,

Thanks for updating this thread. Could you please update to the latest versions? Our latest versions are:

  • Pro theme 4.1.5
  • WP 5.6
  • PHP 7.4

This latest release contains fixes for several issues so be sure to check out the changelog:

After doing the updates, always remember to clear all caches (if you are using WP Rocket, WP SuperCache or W3 Total Cache) when updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.

If nothing is helping, please create a NEW THREAD and provide us access to your site so that we can check your settings. Please create a secure note with the following info:
– Link to your site
– WP login URL
– WP username
– WP password
– WP Administrator Role
- Confirmation that we can access and make changes to your site

To know how to create a secure note, please check this out: How The Forum Works

Please let us know how it goes.