While the issue:
SyntaxError: invalid range in character class cs-vendor.js:5172:545: is gone now,
The version of X (6.2.5) and Cornerstone (3.0.4) you have is not compatible. this will lead to another issue like it has now:
Uncaught TypeError: Cannot read property 'action' of undefined
I advise that you re-install the X theme to make sure, it is clean (from corrupted files).
You can follow the Manual X Update Via FTP guide provided here, so you can avoid deactivating the X theme. The guide says for updating but the same method can be followed for re-installing.
You can download a clean copy of
x.zip file from the Apex Dashboard.
After you reinstall the X theme, deactivate and delete your Cornerstone (3.0.4), then navigate to X > Validation wait for a few seconds and X will reinstall an updated version of Cornerstone for you.
Another thing, all your X extensions are outdated, please update those as well.
To update the Extensions to the version that is supported by the theme:
- Ensure your theme is validated so Extensions can be installed automatically
- Deactivate and delete the extensions, from the plugins panel.
- On the X > Validation > Extensions locate and install the extensions that you need.
- Visit "Plugins" panel in your Dashboard to activate the newly installed version.
Because all of the plugin settings are stored in the database, and because version 2.x will migrate settings from older versions, its safe to use this method of deleting the previous version. But always keep a backup of your entire site just to be safe.
You can check what are the latest supported versions from here.
Remember to clear all your caching features (plugin, server-side, CDN, and browser's cache) after updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.
If the issue persists after this updates, please contact your hosting and ask how you can upgrade the PHP version to 7.0 or 7.1.
Let us know how it goes,