Cannot publish, update, or save draft.

[amdphreak]

Cannot update any posts with Classic Editor. Just installed it. It views and lets me edit them, but I can't update or save draft. When I click the button to update the post, it gives this error notification:

Saving of draft failed.

There is no way to un-publish or re-publish a page with the modern editor, so this editor should be an official part of the main project.

"Even in the future, nothing works!" -Dark Helmet