Add or remove blocked file types Use this procedure when you want to prohibit files of a specific type from being saved or retrieved from any web application on a server. To add or remove blocked file types by using Central Administration Verify that you have the following administrative credentials. You must be a farm administrator on the server. In Central Administration, click Security . On the Security page, in the General Security section, click Define blocked file types . On the Blocked File Types page, if you want to change the selected web application, on the Web Application menu, click Change Web Application . Use the Select Web Application page to select a web application. Do one of the following: To block an additional file type, scroll to the bottom of the Type each file name extension on a separate line text box, type the file name extension that you want to block, and then click OK .