Javascript & Ajax failed to load on many pages like field editing & views editing pages.
Jquery Update module is very helpful but new jquery versions can cause issues with other dependent modules. The module is important not only to keep your site up to date but also allow for theme-specific control to ensure compatibility. So the module's settings page is something you might want to visit and test when a new jquery version is released.

Also, the CDN option can cause load issues if the provider you choose is offline for some reason or overloaded. From the jquery update settings warning:


  "NOTE: Using one of the "CDN Provider" options below is the preferred
  method for loading Bootstrap CSS and JS on simpler sites that do not
  use a site-wide CDN. Using a "CDN Provider" for loading Bootstrap,
  however, does mean that it depends on a third-party service."


So use this option with caution.