[5.x]: Issue with CKEditor After Craft CMS Update

What happened?

Description

I am experiencing an issue with CKEditor after updating to the latest version of Craft CMS. My website went down, and I am seeing the following error:

craft\ckeditor\Field::craft\ckeditor\{closure}(): Argument craftcms/cms#1 ($entryType) must be of type craft\models\EntryType

Steps to Reproduce

1. Updated Craft CMS to the latest version using composer update.
2. After the update, CKEditor stopped working and displayed the error above.

Steps Taken to Fix the Issue

I was able to resolve the issue by performing the following steps:

php craft clear-caches/all
composer remove craftcms/ckeditor
composer require craftcms/ckeditor
php craft project-config/rebuild

Additional Context

• I did not make any manual changes to CKEditor’s configuration before updating.
• The issue only appeared after updating Craft CMS.
• Reinstalling CKEditor and rebuilding the project config fixed the issue.

Would appreciate any insights on whether this is a known issue or if a fix is planned in a future release.

Craft CMS version

5.6.10.2

PHP version

8.3.17

Operating system and version

Linux 5.10.0-33-amd64

Database type and version

MariaDB 10.6.21

Image driver and version

Imagick 3.7.0 (ImageMagick 6.9.11-60)

Installed plugins and versions

1. CKEditor 4.6.0
2. Freeform 5.9.15
3. Minify 5.0.0
4. Olivemenus 5.0.0
5. Sprig 3.5.2
6. Super Table 4.0.3

Start by reproducing the error after updating Craft CMS with CKEditor 4.6.0, PHP 8.3.17, and the listed environment. Compare the failing state with the reported workaround of reinstalling CKEditor and rebuilding project config. Done means identifying a reproducible cause and defining a verified fix for the EntryType argument error.