Akeeba Backup for Joomla!

#35886 Restoration of Joomla 3.9 site with Joomla 3.10 update component

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Environment Information

Joomla! version
PHP version
Akeeba Backup version


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Description of my issue:

I had a Joomla site updated to version 3.10.2, but after updating the Helix Framework template, I got an error. So I restored to my last backup where Helix was running fine. This was a Joomla 3.9.28 site (a backup from a month ago)
Now I want to update this site to the latest Joomla version, but strangely enough when I go tho the Joomla update component, I get a page with the Joomla 4 pre update checker (where there's no language translation). If I go to the second tab and check the ignore errors checkbox, I can't go further. The update button doesn't work. It seems like Joomla is trying to update to version 4. 

In the options the update chanel is set to Standard.

I did a database update in Joomla. Now I get an error in the Joomla updater: Class 'JAdapter' not found.

What's wrong here? 

Akeeba Staff

You can't restore a Joomla 3.9 backup on top of a Joomla 3.10 site. Please read

Do not try to overwrite one Joomla! version family with a different one. Overwriting a major version with another (e.g. restoring a backup taken on Joomla! 3.7 on top of a site running Joomla! 2.5 or vice versa) or between different minor versions (e.g. restoring a backup taken on Joomla! 3.7 on top of a site running Joomla! 3.6 or vice versa) will NOT work. Joomla! moves files around between minor and major versions. Since the backup does not delete files not present in the backup archive this will end up with Joomla! being "confused" and malfunctioning. In these cases you should delete the existing files and folders (except, perhaps, user generated content) before restoring the backup. You can safely restore a sub-minor (path-level) version on top of another. For example, you can safely restore a Joomla! 3.7.5 site on top of a Joomla! 3.7.3 site or vice versa.

After doing that you will have no problem with the restored site.

Nicholas K. Dionysopoulos

Lead Developer and Director

🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!


Thank you for the clarification. So if I only have a backup from a previous Joomla version, then I need use the backup file and Kickstart to reinstall the previous version of a site? (For example if I updated from Joomla 3.9.28 to Joomla 3.10.2, and noticed the update turned out wrong)

Akeeba Staff


Nicholas is currently busy so I'm taking this ticket.

The best thing to do is to delete all files on your server (where you have a mixed version between 3.10 and 3.9) and restore your backup that has been taken before the update to 3.10.


Triple check that your backup is actually working and is not corrupted, moreover do an extra copy to save it somewhere.
You might want to download ALL your backups and store them securely.

You are going to completely nuke your site, so you should be 110% to have a working copy of your site.

Davide Tampellini

Developer and Support Staff

🇮🇹Italian: native 🇬🇧English: good • 🕐 My time zone is Europe / Rome (UTC +1)
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!

System Task
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