Hi There,
Thank you for writing in, you updated the X to the latest version (6.3.6) but you leave the Cornerstone behind. Please update the Cornerstone to the latest version as well (3.3.6).
You can easily update the Cornerstone by deactivating and deleting it, then navigate to X > Validation dashboard, wait for a few seconds and X will automatically install a compatible version of Cornerstone.
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.
And since you’re using VC, navigate to WPBakery Page Builder Settings > General Settings and make sure “Legacy X Integration” is enabled. A common request we get is to not overwrite parts of the WPBakery Page Builder. We are committed to keeping supporting sites from the early days of X where Visual Composer was our page builder but we’ve consolidated all that integration code under one setting. It used to be enabled by default, but you will now need to opt-in to use it.
Release Notes - Pro 2.3, X 6.3, Cornerstone 3.3
Hope it helps,
Cheers!