Attack of the Inconsistent & False-Negative TMG Test 404 Error

Description:

Within an environment that uses a Microsoft Forefront TMG array as the reverse proxy for Lync 2013 and Office Web Apps I had an error flag when testing a web publishing rule.  This specific rule was to relay traffic to a Office Web App farm.

Category: General error
Error details: An unexpected response was received from the server.  HTTP response: 404 No Found
Action: Verify that the intended server is published and that virtual directories exist.  Ensure that you can browse the published site directly from an internal client computer.

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Take note the error appeared only on one TMG server at a time and it changed between the two at random.  There are two Office Web App servers in the farm.  It made sense IIS or the OWAS webpage had issues on one of those two servers.  However, I was able to browse the OWAS site successfully at https://localhost/hosting/discovery.

I was also able to connect successfully to this site on both OWA servers from both TMG’s, different internal client PC’s and also externally through the TMG.  So it appeared there was actually no loss of service while this error continued.

Resolution:

After longer than the time it should have taken, I determined this publishing rule test is only checking the root (ie: https://localhost/ or https://OWASfqdn.domain.com/)of the IIS site on each OWA Server.  It is not the page of the actually OWA server within sub folder /hosting/discovery.  I checked both OWA server’s root and noticed one had a blank default.htm while the other did not.

When attempt to browse https://localhost locally on the one that did not I magically had a HTTP 404 Not Found.  This is due to the simple fact that there’s no default document in this root location to load.

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The final fix was to create any .html file that matched a default document name (ie: default.htm) and place it in the root website location C:/Program Files/Microsoft Office Web Apps/RootWebsite.

From here if you browse https://localhost you should see your blank page or whatever you place there.  Lastly, if you re-run your TMG web publishing rule test for your Office Web Apps farm you should now hopefully have nothing but green.

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I also knocked out about 100 push ups since it’s such an obvious yet stupid mistake.

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