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Joomla 5.4.3 Known Issues

Last Updated: 2 March 2026

Joomla 5.4.3 was released on 17 February 2026.

Issue 47238 – Firefox 148.0 indefinite TinyMCE refresh​

Firefox version 148, released on 24 February 2026, causes the TinyMCE editor to flicker and content to load endlessly, making it impossible to edit article content. See Bugzilla Bug 2019320.

Resolution​

This issue will be resolved in Joomla 5.4.4 by PR 46889.

Workaround (Before Joomla 5.4.4)​

  1. Use a different browser or a version of Firefox earlier than 148.
  2. Install the hotfix from the Joomla! 5.4.3 Firefox 148 TinyMCE Hotfix1 section on the Joomla! 5.4.3 download page.
    • Download the ZIP file and verify it against the checksum shown on the download page.
    • Install it via System → Install → Extensions
About this hotfix package (technical details)

What is this?​

This package is a one-time file patcher for Joomla installations. It applies specific Joomla core file changes before they are available (or fully backported) in an official Joomla release.

It is intentionally distributed as a file extension with an installer script so it can:

  • apply patched core files automatically,
  • clearly report what was changed,
  • and remove itself immediately after execution.

After a successful run, no extension remains installed.

Supported Joomla versions​

This patcher only runs on the following exact Joomla versions:

  • 5.4.3
  • 6.0.3

If installed on any other Joomla version:

  • the patcher will abort safely,
  • no files will be modified.

This strict version check is intentional to prevent applying patches to unknown or incompatible code bases.

What happens during installation?​

  1. Joomla starts the installation process.
  2. The installer script verifies the Joomla version.
  3. The patched core files are copied into place.
  4. A summary message is shown, indicating:
    • how many files were applied,
    • how many failed,
    • how many target files were missing.
  5. The patcher removes itself automatically.
  6. The installation completes.

No manual clean-up is required.

Is this safe to use?​

Yes, provided that:

  • you are running exactly one of the supported Joomla versions,
  • you understand that this applies core file changes,
  • you have appropriate backups in place (as recommended for any core modification),
  • you downloaded this package from one of the official Joomla websites.

The patcher:

  • does not modify the database schema,
  • does not install plugins or overrides,
  • does not persist after installation.

Removal / rollback​

Because the patcher removes itself automatically:

  • there is nothing to uninstall manually.

To roll back the applied changes:

  • reinstall the Joomla core files via the administrator interface, or
  • restore the affected files from a backup.