Saving Error after re-order images

Mar 8 at 4:09 PM
When trying save or the "reorder" screen I receive the following error " An Error Occurred... There was an error saving your changes. Please try again later." Running DNN 8. Happens in all browsers, clear DNN cache, restarted and recycled the app.

The following warning is also in the browser console "Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience." which may or maybe irrelevant. and a 404 on /DesktopModules/WillStrohl.LightBoxGallery/ImageOrder.a…9%2C10%2C11%2C12%2C13%2C14%2C15%2C16%2C17%2C18%2C19%2C20%2C21%2C22%2C23%2C

Any ideas what this could be?