Hoi Taco,

your question is for forum.joomla.org, becuase it's about Joomla itself.

Enable debug mode to find the culprit

You need to determine which specific file (extension) is calling this nonexistent method.

1. Log in to your server via FTP or the File Manager in your hosting control panel.
2. Open the configuration.php file in the Joomla root directory.
3. Find and change the following two lines (set them to debug and maximum error reporting):

    public $debug = true;
    public $error_reporting = 'maximum';

4. Refresh site. Now, instead of a general message, you'll see what's called a stack trace (error tree). You'll see the exact path to the file and the line number. The path will tell you whether the problem is in plugins/, modules/, or templates/.

I can also log in and enable debugging. If I visit the site now, I see a lot of lines, but I’m not an expert.

In your case problem is with outdated component & module unitegallery (!) remove it.

Thanks, Paul. When I select 'uninstall' under extensions, it doesn't work either; is there another solution for that?

Not our product = beyond joomshaper support.

ok

ok

solft

Ok, please mark topic as solved