Webresource.axd doesn't load on my asp.net application running on my web farm

Answer 1

• Make sure all the servers have the same asp.net version. Something that could affect it, is partially applying the recent Microsoft patch for the padding oracle vulnerability (to some servers, instead of All)
• Make sure all the servers use the same machine key. When doing so either use protected sections or configure it at the machine level web.config / learn from the recent vulnerability to protect sensitive information in the web.config.