I recently ran into a problem with not being able to edit or even add a new category on a Magento site. I was upgrading a site and was working on the Development installation. I had changed the site name from something like “localsite.com” to “localsiteUpgrade.com”.

All of the sudden I could not edit categories. The problem is that when I viewed the site it showed as “localsiteupgrade.com” the “U” in Upgrade got converted to “u” lowercase. This difference in the base url set in magento and the url in the browser was causing SID to appear in the url. This was breaking ajax urls like the ones used to edit categories. to fix the issue I just had to set the base site url to “localsiteupdate.com” like it was showing in the browser address bar. Durring my research I ran accross other posts showing how to use htaccess files to make sure that visitors were redirected to the proper url.

Hope this saves someone else some time!