Migration to Joomla 4.x goes wrong!

[fruiter]

Last 2 weeks I tried to migrate to Joomla 4.x. I checked the status of packages and decided to migrate. This went wrong, the migration process crashed, my website did not work anymore.

Now I restored the backup of the database and the webspace. My website runs fine now, but Joomla does not work anymore! I cannot do anything with the Joomla dashboard, every page gives an error!

Today I tried to reinstall my existing Joomla 3.x version to see whether that resolves the issues, but unfortunately this crashed as well. No joomla anymore and no website anymore. So I restored the backups again.

What do I need to do to resolve this? I cannot maintain my website anymore with Joomla, but migration does also not work. Who knows what to do?

[gws]

You must delete all files in the joomla directory and empty the database before you restore to your original version,going from j3 to j4 changes the structure of J that is why you have to start from a clean directory and DB.

[AMurray]

Did you migrate from 3.10.x? That is the only version from which you can upgrade to 4.x. Did you ensure your extensions were 4.x compatible, and follow any advice of the pre-update checker report?

How did you backup and restore - with Akeeba Backup and Kickstart (or another backup extension) or through your web host (cPanel backup/restore), or manually re-uploading the joomla system files and importing the *.sql file into phpMyAdmin?