Response.Write(qdbXml); Response.Flush(); Response.Close();So while cleaning up some other code I removed the Flush() call. Then everything stopped working. I thought it was the other changes I made at first. Chrome gave this helpful message:
Error 324 (net::ERR_EMPTY_RESPONSE): The server closed the connection without sending any data.I restored the Flush() and everything worked great again. The Response object above is a System.Web.Mvc.Controller.Response object which doesn't necessarily work like some other stream objects and needs flushing before closing.
TIL not all stream objects behave alike and I can get in trouble by assuming hastily gathered Googled results apply to me.