Your version of X and Cornerstone is not compatible. Please update both X and Cornerstone to the latest version (X 6.3.3 / CS 3.3.3)
Updating Your Themes and Plugins
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.
Also, update these two themeco extensions X – Content Dock and X – Smooth Scroll
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.
Hope it helps,