Quick update: For my part the thread can be closed.
As mentioned above, it helped to create the "system_data" column in the extensions table.
Nevertheless the update had a lot of mistakes so I decided to install Joomla 3 fresh, import only the essential tables in the new database an make the update.
That was successful and I now have a working (altough not yet good looking) Joomla 5 page with all articles and menus and modules I need.
As mentioned above, it helped to create the "system_data" column in the extensions table.
Nevertheless the update had a lot of mistakes so I decided to install Joomla 3 fresh, import only the essential tables in the new database an make the update.
That was successful and I now have a working (altough not yet good looking) Joomla 5 page with all articles and menus and modules I need.
Statistics: Posted by Roland_S — Thu Apr 18, 2024 5:52 am