Support

The problem you are experiencing is not caused by Akeeba Backup itself, i.e. it's not a bug. The method being called, setDocument(), has existed in the core Joomla MVC classes since Joomla 4.0 was released back in 2021. Your problem says that either some files are missing from the component, or there's a third party system plugin getting in the way.

Beyond that, I would like to note that you are using an End of Life version of Joomla with a version of Akeeba Backup that was never meant to be used and has not been tested with your Joomla version. You can find this information in our Compatibility page. I want to make clear that this IS NOT the root cause of your problem. It does, however, mean that we are not going to provide any further assistance as you are using a version of the software we have not designed for Joomla 4.3, and because we stopped providing support for Joomla 4.3 three years ago.

The last version of Akeeba Backup supported on Joomla 4.3 was 10.0.2, released back in February 2025. Kindly note that this version, just like Joomla 4.3 itself, is End of Life and will not be supported either. You are on a dead version of Joomla.

I would recommend making a copy of your backups, uninstall the Akeeba Backup 10.3 package extension –not just the component!– knowing that this will delete the backup records from the database and any backups stored under the default backup output directory, and install Akeeba Backup 10.0.2 with the sole and explicit purpose of taking a backup of your site before upgrading it. You should first upgrade to Joomla 4.4, and then to Joomla 5.4. In two to three months we will not be supporting any versions of Joomla older than that.

if the problem persists, try disabling system plugins one at a time and retest. When it starts working again you know that the last system plugin you disabled is the culprit. You can ask its developer for support, albeit they will probably tell you the same thing: you are on a dead version of Joomla, therefore you need to update.