Figured it out. I used that same URL in a browser and got a more meaningfull error:
HTTP Error 403.18 - Forbidden
The specified request cannot be processed in the application pool that is configured for this resource on the Web server.
Checking the app pool showed that the FMS stuff used the application pool "DefaultAppPool" and the IIS default web site used "default application pool". Changing the FMS test page to that pool didn't work because when you retry the deployment wizard, the FMS installer changes it back to "DefaultAppPool". That "DefaultAppPool" did not exist in my available application pools so I manually created it, set it as the app pool for the whole default web site and voila... the deployment wizard was able to connect to IIS and complete the installation.
Thanks for tracking that down, Wim. Something for the knowledge base?!
-- sent from my iPhone4 --
Yeah, I think this needs to be in the knowledge base. Simple enough fix but it's knowing that it depends on the "DefaultAppPool" application pool that is the killer.
Article 10228 would be a good spot to put it in...
Is this different from the install note about anonymous authentication? From http://help.filemaker.com/app/answers/detail/a_id/10248
Using FileMaker Server with web publishing on Windows Server 2008 requires IIS 7 (Internet Information Services 7.0) anonymous authentication to be enabled. When installing FileMaker Server on Windows Server 2008, if IIS 7 anonymous authentication is disabled then the Deployment Assistant cannot find IIS 7. By default, IIS 7 uses IUSR as the user name for anonymous access. Enable IIS7 anonymous authentication before installing FileMaker Server if you are going to use web publishing.
Yes it is. On that particular server, Anonymous access was already set up correctly when I got that error.