error during installation, no access to the administrator and website

[gvdbeek]

during installation from joomla 3 to 4, after 90,8% of the installation I got an error, the installation stopped and the website http://covcantatedeo.nl as wel as the administrator unit could't be accessed anymore.
How can I restore my website and administrator unit?

[Webdongle]

Please describe the steps that you took to install Joomla.
Also please run https://forumpostassistant.github.io/docs/ and post the results here.

[toivo]

Did you happen to copy the error message or take a screenshot and save it?

[AMurray]

As the error is the "sorry there was a problem we couldn't recover from" (Error 500), can you turn on the Debugging and Error Reporting? Both or either will give further information on the actual error.

In the configuration.php file, you can turn these on, and in your hosting system (cPanel for example) you can turn on PHP error reporting (the reporting may already be on, but logging errors to a file; you can turn on "display_errors" which will show them on screen).

[gvdbeek]

At the moment I have no access to Administrator. I only see the files when I use FTP, but where can I find the error report?

As webmaster of our choir, I enjoyed working with Joomla until recently, although I don't really have an ICT background. However, after the last updates I received an error message and as a result I tried to install Joomla 4. Unfortunately, the installation stopped after 85.6% and gave an error. The result: no website anymore and no administrator. I could still see the files via FTP. Looking for a solution I found Kickstart from Akeeba and yes, there was the website again (joomla 3) and I could also go back to the administrator part. Unfortunately, everything was said with the latter, because as soon as I wanted to change something, there was another error message. I was still able to access the update section and tried to reinstall Joomla 3. Again the update process stopped at 85.6% and I could start kickstart again from scratch.

Now my last backup was gone, so I put the one from 2020 on it. With the same result again, an (outdated) website, but no well-functioning administrator part. Made another attempt to reinstall Joomla with the same result again.

Back to Kickstart, but now all backups were gone and I am afraid that if I use this again my entire website of 2020 will also disappear and then we have nothing left.
Who knows a solution for this? (Please in understandable language, because as mentioned earlier, I am not an ICT specialist).

[gvdbeek]

Did you happen to copy the error message or take a screenshot and save it?

Class 'JFormFieldTextarea' not found

[gvdbeek]

Did you happen to copy the error message or take a screenshot and save it?

Class 'JFormFieldTextarea' not found

Class 'JFormFieldPredefinedList' not found

Class 'JFormFieldGroupedList' not found etc

[AMurray]

Turn on "debug" in the configuration.php file.

Turn on error reporting through your web hosting control panel.

Running the FPA doesn't require access to joomla. it's a single script, uploaded to the server, placed in the same folder Joomla is located, then you just run the script from the browser like yourdomain.com/fpa-en.php