Hi
- if you can still access the admin, download the same version from the download area and install over using the Joomla normal installer
- if you cannot access the admin, use FTP or your hosting company control panel to rename the folder /plugins/system/forseo to something else, for instance /plugins/system/disabled.forseo and then download and install again.
IF possible, BEFORE you do anything, it'd be great if you could enable Debug mode so that we get a more accurate error message and know where the error originated from.
Again, if you can access the admin, enable Debug mode in Joomla global configuration and reload the 4SEO page, this should give a more detailed error message, paste it in full here.
If not able to access the admin, you can open the configuration.php file at the root of your site with FTP or you hosting company file manager and change:
public $debug = false;
to
public $debug = true;
then save, reload the page and paste the full error message. You can then revert the change in configuration.php.
If you're on Joomla 3, instead of public $debug = false;
, you will have public $debug = '0';
, which needs to be changed into public $debug = '1';
Best regards
Yannick Gaultier
weeblr.com / @weeblr