IIS logs status code 590

This is my understanding of the issue so far:

• sc-win32-status 64 means “The specified network name is no longer available.”
• After IIS has sent the final response to the client, typically it waits for an ACK message from the client.
• Sometimes clients will reset the connection instead of sending the final ACK back to server. This is not a graceful connection close, so IIS logs the “64” code.
• Many clients will reset the connection when they are done with it, to free up the socket instead of leaving it in TIME_WAIT/CLOSE_WAIT.
• Proxies tend to do this more than others do.

Update: I found some interesting information here and here, so I basically re-wrote the page to ensure there wasn't any bad markup etc. and... the problem is now gone! It was just a shot in the dark, and I couldn't definitely say what it was that fixed the problem, since it was only affecting some of our clients under some very specific circumstances...

I have not used the msDeploy handler before (we use the agent extensively), but you could try enabling Failed Request Tracing in IIS to determine what the problem is. It's easy to turn on and gives you a lot more info about the request and why it returned a 404 than what the IIS logs will tell you.

Your suspicion about the handler not being installed/configured correctly seems correct and the failed request tracing would show you more about what went wrong with the handler.

http://blogs.msdn.com/b/benjaminperkins/archive/2012/01/02/enable-and-activate-failed-request-tracing-rules.aspx