When changing the language multiple times on the "Add Product" page, the URL accumulates multiple ?lang= parameters, leading to a broken or confusing URL structure. The language change script doesn’t remove the previous ?lang= parameter before adding the new one, causing the issue. How to fix: Update the JavaScript to remove any existing lang parameter from the URL before appending the new one. Example fix: var actionUrl = $('#ajaxReloadForm').attr('action').replace(/\/action. $/, '').replace(/(\?|&)lang=[^&] /, ''); var separator = actionUrl.indexOf('?') === -1 ? '?' : '&'; window.location = actionUrl + separator + 'lang=' + $(this).val(); This will ensure only one ?lang= parameter is in the URL at any time.