The following solution is only for CS-Cart 4.2.x users who upgraded their Twigmo add-ons to version 3.5 before August 7, 2014.
1) Download the upgrade_center.post.php file attached to this article to your local computer;
2) Upload the downloaded file to the app/addons/twigmo/controllers/backend/ directory of your CS-Cart 4.2.x installation overwriting the existing file;
3) Follow the instructions to upgrade your Twigmo add-on to version 3.6 in the automated way.