Body content no more visible in edit mode.

Are there browser console errors? Does Drupal log errors?

There are no browser errors or Drupal log errors.
The phenomenon apparently occurs not only when editing but also when creating a new page. Here there is no option to add content. HTML selection doesn't matter.
Cannot add content to body

I've got this problem on 3 sites on different servers. Unfortunately rolling back to 10.2.7 is an ugly option because of "3456958-bookoutline-plugin-does" which prevents updating content. I say ugly option because uninstalling the Book module requires deleting all content in books. I'm stuck with 3 sites unable to move forward (or backward).

I got the same problem in my sites and it's impossible to rollback to 10.2.7. No errors shown in watchdog, browser, etc. Impossible to create or edit any node's body field.

Maybe related with:

Indeed, I also found that after uninstalling CKEditor5 (and CKEditor Font) and then reinstalling (both), the problem was gone. It's just a pity that the HTML configuration settings are lost and have to be entered again.

@jjgw I have tried it but uninstalling and reinstalling doesn't work for me :-(

I disabled "CKEditor5 Line Height" to fix things.

If you're experiencing this issue, please confirm whether you have https://www.drupal.org/project/ckeditor5_line_height → installed and whether uninstalling the module fixes things.

Uninstalled Line_height AND Font which fixed things. Will try uninstalling CKEditor5 and reinstalling the whole kaboodle; #7 makes this sound like a solution; however if #8 proves to be my case too, then I'll live without Line_height and/or Font.

I've opened 🐛 Incompatible with Drupal 10.3.0 Active .

We do not have CKE5 line-height installed in our site, but still we have the same issue after upgrading to 10.3

@irsar do yo have ckeditor_font installed?

See CKEditor Font → paragraph "Important update information" about this issue.

No we do not have CKEditor Font as well.

I have uninstalled CKEditor Font → and the problem has dissapeared. To replace it I have installed the new CKEditor 5 Plugin Pack → module. It is necessary to re-config a little bit settings but not complicated. The font color settings is different but easy to do. The module joins some other's functionalities (font, size, highlight, etc ...) in one module.

@irsar any other ckeditor5 contrib modules or custom plugins? We need a bit more information to go on if you want help tracking down the issue.

We are using CKE5 Full screen and USWDS CKEditor Integration.

Uninstalling CKE5 fullscreen fixed the issue. I think most of the CKE5 plugins are not compatible with the upgrade. Instead of the CKE5 plugin I tried using the fullscreen in the CKE5 plugin pack and that's working as expected

Dunno whether this might help troubleshooting font and/or line_height: an image I had on some content displayed upside down (!sic) until I removed font & line_height, when it reverted.

The bug is only when i use CKEditor Font Size and Family module with Font Size, Font Family in the tool bare. No problem when Fond Color an Fond Back-Color are used in tool bare
The same bug exists if you use CKEditor5 Line Height module.

We are having the same issue after updating to 10.3.x (specifically 10.3.1) and we do not have the CKE5 font or line height plugins.

I had the same issue - the plugins I had to remove to get my content to reappear were Anchor Link and CKEditor iFrame Embed.

Module CKEditor 5 Line Height is already fixed!
Please, update it to version 1.2.0

I encountered a similar issue, and it was caused by the CKEditor5 template. Downgrading to the following versions resolved the problem for me:

ckeditor5_template: 1.0.5
ckeditor_templates_ui: 2.0.0-alpha3

After applying these versions, everything worked as expected.