I am having some problems with autodiscover. We had an issue with Busy/Free information, this lead to troubleshooting EWS. During this time, the EWS virtual directory got hosed. We recreated the directory/app manually and added to the MSExchangeServicesAppPool.
Our busy/free problems went away and users were able to access the out of office assistant again.
However… ever since then, autodiscover has been failing. If I try accessing the xml file via the web, I get the following error;