I created a wsp and deployed it on sharepoint and with this solution i have created site with custom site template and document libraries also created by code. after that for upgrade i removed that solution and deployed new wsp old and new features. so that old site work properly but in old document libraries after upgrade when i try to create new folder. page not found comes and i am not able to find out reason. it is not able to find upload.aspx. but if i create new document library they are working fine. .version of the dlls are changed. please help . i am not able to trace the issue. please help