Joomla Update

htmanager

I installed JoomSocial 4.7.8 and wanted to upgrade to Joomla 4.0.3. This update failed. After restoring the backup I can't open the configuration sites in Joomla. I get an error message like: Class 'JFormFieldList' not found or Call to a member function order() on null
My ISP has no clue what this could be. I copied the files from a new 3.10.2 version without success. If I open the database all tables are there and accessible.
What can I do to solve this problem?
Thanks in advance,
Juergen

Ninja

htmanager
Hi
Migration is important step in Joomla as if any of extension not ready on your site it can break the site.
I suggest you to restore the site backup and follow the steps as given here : https://www.joomlart.com/blog/joomla-templates/how-to-migrate-joomla-3-to-joomla-4-step-by-step-tutorial
On current submit URL it appear still using Joomla 3.x

Disable all extensions and templates that not ready for Joomla 4 before upgrade and try update on staging site first.