Hello Julian,
Did the errors appear lately? The issue could be because you are using an incompatible version of the theme, the X theme 8.3.3 while you are using the latest version of Cornerstone 6.0.6
. Can you please update the X theme to version 9.0.6
instead? After the update, please make sure to clear all your plugin caches and browser cache and test the site again. If the issue still exists, It could also be caused by a plugin conflict, amongst other things. Please check out this troubleshooting article here and follow the instructions for the following sections (where appropriate):
Testing for Plugin Conflict
Theme Update
Child Theme
Disabling Cache
Disabling CDN
Best Regards.