How To Fix Incompatible Archive Error in WordPress 6.4.3

If you are where trying to update a theme on your WordPress site and you encounter a problem like this, “Incompatible Archive”, then here is a fix. This is an error that occurs in the new WordPress 6.4.3 update. The message pops up when users try to update or upload a new theme. WordPress is aware of this issue and is actively working on a fix.

Cause Of the Error?

The main cause of this error, is the way MacOS compresses zip files and how WordPress 6.4.3 interprets them upon upload. Recent security enhancements aimed at tightening up the upload process inadvertently introduced challenges for MacOS compressed zip files, leading to the dreaded ‘Incompatible Archive’ error message. Similar issues previously affected WordPress and WP-CLI and the behavior ties back to PHP’s libzip version discrepancies.

While we await a bug fix from WordPress, here is a simple and easy work around to the issue. This step will help you fix or guide you on how to install that theme for now, before a new version of WordPress update is rolled out (6.4.4). Now without watsing your time, simply follow the steps below.

What To Do When You Encounter Incompatible Archive Error?

Go to Plugins > Add New. Install and activate WP Downgrade.
Once activated, go to Settings > WP Downgrade.
In the WordPress Target Version box, type 6.4.2. Click Save Changes.
Next, go to Dashboard > Updates and click “Re-Install Version 6.4.2.” This will downgrade you to WordPress 6.4.2.

After downgrading, you can proceed with uploading your new theme as normal on your Themes page.

Once your theme is installed, deactivate and delete the WP Downgrade plugin. You can then either upgrade to WordPress 6.4.3 again or wait for the WordPress 6.4.4 release. Please note that aside this Incompatible Archive issue, the version 6.4.3 works well.