Block Editor No Longer Working: Only Shows HTML

I’ve made lots of changes to my WordPress site recently and now the block editor (i.e. Gutenberg) does not work, nor can I see the Visual and Code tabs on the classic editor when I have the classic editor plugin installed. Here’s the (related?) changes I’ve made, as best as I can remember:

• Installed the new Gutenberg plugin
• Installed the classic plugin
• Added & Connected Jetpack to my site (self-hosted)
• Removed and Added Jetpack, Gutenberg, and Classic editor plugins many times while debugging this issue

Here’s a screenshot of my block editor, notice the block add button is greyed out: Can’t add blocks

Here’s a screenshot of the post where only HTML is shown: Block editor stuck showing HTML

The keyboard shortcut to switch between visual and code (CTRL-SHIFT-ALT+M) does nothing.

When I installed the Classic Editor plugin to see if that helped, I can’t see the visual or code tabs: Classic editor plugin: no visual or code tabs. This was done in troubleshooting mode on 2019 theme and there were no JS errors in the console.

Here’s some more information I’ve gathered and actions I’ve performed in troubleshooting all this:

• First saw this issue in 4.9.8, upgraded to version 5.0.0, and now upgraded to 5.0.1. This is still a problem.
• Run health check and have done all this with troubleshooting mode on and all plug-ins disabled
• With troubleshooting mode enabled, there are no JS errors in the console
• Verified that the option to disable the visual editor is unchecked for my user account
• With Jetpack connected to the site, I was able to edit posts and pages using the Visual/Code editor (no Gutenberg, but I think that requires the plugin?). But editing posts and pages in wp-admin still showed the problems I’m describing. I worked through it with Jetpack support, but since it’s not really an issue with Jetpack I’ve migrated to the support forums.
• Checked for related cases, and they either don’t apply or the solutions don’t work:

• Closest! but not the right solution:Visual Editor Missing, Server-Side Problem, How Would You Debug It?
• https://wordpress.org/support/topic/visual-and-block-editor-are-gone/#post-10901541
• Visual Editor not working when Jetpack plugin is active

I’d appreciate any assistance. I can do HTML, but I’d rather have access to HTML and the new block editor!

I’m happy to include any more information that would be helpful.

• This topic was modified 7 years ago by James.
• This topic was modified 7 years ago by James. Reason: Add WP version when problem started and has continued through subsequent WP versions