Fails on Drupal 9.5+

Since the field should not save its value, but only the settings, we can fix the problem by implementing the isEmpty() method and always return TRUE. But entities that was created before the patch applying will still produce the error.

Hi Steven Snedker,

I confirmed the issue was resolved when I applied patch #4 to the "Readonly Html Field" module against Version 1.0.1. Please see the screenshots attached.

For your review.
Thank you.

Pinging @wombatbuddy and @Steven Snedker :)

What would be great, is if the error message could be more precise, and pin point that the source of the error message is that the contrib module "Readonly Html Field" allows an empty value (as I understand it) ...

From ✨ Improve error messages, by including the source Active .

It would be awesome if you could share your observations in that issue, so we can get better feedback to more easily backtrace Drupal errors. Thanks!

Thank you guys, @wombatbuddy patch's has been committed
Anyone facing this issue should update to Readonly Html Field 1.0.2 version → and then execute drush updb to clean up erroneous data from "Read-only html field" fields.