Critical error - Call to undefined method TGM_Plugin_Activation

As soon as I try to update X from 8.0.11 to 8.1.3. I got the following error:

There was a critical error on your website. Please check the inbox of your website administrator email address for further instructions.

Ein Fehler vom Typ E_ERROR wurde in der Zeile 55 der Datei /home/travelth/ verursacht. Fehlermeldung: Uncaught Error: Call to undefined method TGM_Plugin_Activation::is_plugin_activated() in /home/travelth/
Stack trace:
#0 /home/travelth/ X_Validation_Cornerstone->maybe_show_notices(’’)
#1 /home/travelth/ WP_Hook->apply_filters(’’, Array)
#2 /home/travelth/ WP_Hook->do_action(Array)
#3 /home/travelth/ do_action(‘admin_notices’)
#4 /home/travelth/ require_once(’/home/travelth/…’)
#5 {main}

I also deleted X and Cornerstone manually and uploaded the newest version via FTP. But I got the same error. Cornerstone is ok, but as soon as I update X I got the critical error.

What can be the reason for this and how can I fix it?

Hello @michaelxxx,

Thanks for the details. Please delete Cornerstone first. Update the X theme and then go to X > Validation to install the bundled version of Cornerstone. If nothing is helping, 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

Best Regards.

Before I try this, a general question: why are there so many problems updating X? The forum is full of critical error messages.

I´m a user of X since more than 5 years… and there have never been so many errors during the update.

Hi @michaelxxx,

It might be due to the improper up-gradation of the Cornerstone plugin. Like my colleague suggested I would also suggest you follow the below steps and update the Cornerstone once again.

  1. Delete the Cornerstone existing one
  2. After deletion please use the link in the dashboard to automatically install the Cornerstone.

If that does not resolve the issue, I would suggest you troubleshot a few common issues to find the reason behind them.

1.Plugin Conflict
2.Child Theme Related issue ** if you have activated it.
3.CSS/JS Customization
4.Disabling Cache

If you discover that an issue is coming from a custom code or 3rd party plugin, kindly consult with a developer or contact the plugin author. Please note that we do not provide support for custom codes and 3rd party plugins.
If none of the above help, please provide login credentials for your site in a secure note to examine it further, including:

– WordPress Site URL & Login URL
– WordPress Admin username/password

To create a secure note, click the key icon underneath any of your posts.


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