Installation and setup

Adding CKEditor 4 LTS module to Drupal 9/10

CKEditor 4 reached its end-of-life. If you are interested in extended support for CKEditor4, please visit: https://ckeditor.com/ckeditor-4-support/

This project is a copy of https://www.drupal.org/project/ckeditor a with an upgraded CKEditor library to the LTS version. It shares the same namespaces and machine names.

If you already use CKEditor, this module will override the existing one with the LTS build of CKEditor 4.

Installation:

If you have not used the ckeditor module before, simply download the ckeditor_lts module and enable it, then go to /admin/config/ckeditor-lts/settings, and enter your license key.

If you use Drupal 9 or have already installed https://www.drupal.org/project/ckeditor you can enable this module in two ways.

First method

1. Download ckeditor_lts into your project and make sure to clear an APCu cache or any alternative you use. 
   In the case of APCu, you can visit /admin/config/ckeditor-lts/settings and click the clear cache button under advanced settings.
2. Go to /admin/config/ckeditor-lts/settings and enter your license key

Second method

1. Export all configs related to editor and text formats.
2. Uninstall CKEditor module and make sure that ckeditor directory is deleted from the project files.
3. Add ckeditor_lts module to your project and enable it.
4. Import all configs related to editor and text formats
5. Go to /admin/config/ckeditor-lts/settings and enter your license key.

Uninstallation

In case you don’t want to go back to the non-LTS version of CKEditor 4 and completely remove the module (for example in case of migration to CKEditor 5) uninstall the module as any other module. Otherwise please follow instructions below:

1. Make sure that the old CKEeditor module is present in contrib modules directory.
2. Remove the ckeditor_lts module from files or run composer remove drupal/ckeditor_lts
3. Clear APCu (or any alternative you use) cache manually or using Drupal rebuild (instruction below)

Clearing APCu/WinCache using Drupal rebuild

APCu can be cleared with Drupal. In order to achieve this, access to the server's console is required.

1. Access the site’s server console
2. Run a shell script located in {DRUPAL_ROOT}/web/core/scripts/rebuild_token_calculator.sh. The output will contain the timestamp and token query parameters. Copy the whole string.
3. In a browser window go to /rebuild.php?{COPIED_VALUE}

The user cache will be cleared. It is necessary to clear the cache if you already had the old CKEditor module installed.