Cornerstone 5 doesn't work on my site

I just went to edit a page on my site and learned that the newer Cornerstone (5.0.11) isn’t working on my website.

Every page on my site cannot be edited because the Cornerstone preview errors with: “The preview could not load due to the iframe response being incomplete. This is most often related to a plugin conflict, or customizations introducing a PHP error.”

I have a staging site with Cornerstone Version 4.2.3 and it’s fine.

How can I downgrade to Version 4.2.3 on my production site?

Now I’ve discovered that a number of pages are down with this error:

Fatal error : Uncaught ArgumentCountError: Too few arguments to function Cornerstone_Element_Front_End::begin_excerpt(), 1 passed in /wordpress-versions/5.5.2/wp-includes/class-wp-hook.php on line 287 and exactly 2 expected in /dom33971/wp-content/plugins/cornerstone/includes/classes/elements/class-element-front-end.php:40 Stack trace: #0 /wordpress-versions/5.5.2/wp-includes/class-wp-hook.php(287): Cornerstone_Element_Front_End->begin_excerpt(’’) #1 /wordpress-versions/5.5.2/wp-includes/plugin.php(206): WP_Hook->apply_filters(’’, Array) #2 /dom33971/wp-content/plugins/gamipress-progress-map/templates/progress-map.php(45): apply_filters(‘get_the_excerpt’, ‘’) #3 /wordpress-versions/5.5.2/wp-includes/template.php(732): require(’/dom33971/wp-co…’) #4 /dom33971/wp-content/plugins/gamipress/includes/template-functions.php(191): load_template(’/dom33971/wp-co…’, false) #5 /dom33971/wp-content/plugins/gamipress/includes/template-functions.php(140): gamipress_locate_template(Array, true, false) #6 /dom33971/wp-content/plugins in /dom33971/wp-content/plugins/cornerstone/includes/classes/elements/class-element-front-end.php on line 40

There has been a critical error on your website.


Update: I uploaded a copy of Cornerstone: Version 4.2.3 and was able to get back up and running.

Hi @dean44,

Glad to hear you’re back up and running. If you do want to attempt to update to the newest version of Cornerstone, I would suggest you update on your staging site and then test for a plugin conflict. Check out the article here for instructions on how to do this.


OK, here’s how I fixed it. I tried no plugins activated except for Cornerstone, but that didn’t fix it. I tried different themes, etc, and I figured out that the conflict was between X Theme v7 and Cornerstone! X Theme v8 and Cornerstone work fine together… but why that didn’t update properly the first time, I have no idea.

Hi @dean44,

I guess it is an improper way of upgrading your theme and cornerstone plugin that’s why you’re having an issue. For future references, I suggest that when you update your theme to the latest version, please delete the cornerstone plugin first to avoid any conflict then update your theme to the latest version and install the cornerstone plugin again.

Hope that helps.

Thank you.

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