The base type 'System.Web.UI.MasterPage' is not allowed for this page. in General Posted March 17, 2009 · Report reply I have installed the software on a server with Windows 2003 SP1 and WSS3.0. I get two errors: 1. Trying to load the default sharepoint site (port 80): The base type 'System.Web.UI.MasterPage' is not allowed for this page. The type is not registered as safe. 2. I can load other sites (ie. port 8087), but when I try to configure a FX Webpart I get: File Not Found. Web Parts Maintenance Page: If you have permission, you can use this page to temporarily close Web Parts or remove personal settings. For more information, contact your site administrator. HOW CAN I RESTORE MY DEFAULT (80) SITE?.