Thread:Project:Support desk/Unable to make changes to unprotected pages/reply (3)

Since it requires login to edit I cannot directly test it, but I inserted manually a preview form on that page and it indeed redirected to main page.

Set up a debug file and see what it prints just when hitting preview. If the redirect is done by MediaWiki, you should see a POST request (when hitting preview) and then a GET request of the main page. If the redirect is done by the web server without the intervention of MediaWiki, the POST request won't appear on the logs.