It happened when trying to surf a directory under IIS7 environment that contains special character symbol and return you HTTP 404.11-Not Found error. Example Url : http://localhost/directory/A+B+C/filename.html By default, IIS 7.0 rejects URLs that contain a double escape sequence. WorkAround 1. Open web.config and add <system.webServer> <security> <requestFiltering allowDoubleEscaping=”True”/> </security> </system.webServer> </configuration> 2. Save