I am working on some internal training at the moment on the use of alternative authentication methods for WSS and Project and am playing about with LDAP. Having shot myself in the foot by leaving a web.config open and then later saving it over a version that WSS had modified I thought I would take a look at the option within InetMgr (IIS Manager) that allows the editing of the web.config and a nice little UI. Perhaps safer than notepad? I was setting WSS to use two different LDAP providers on two different ports - but the Central Admin site needs to know about both of them. Uncharted territory for me - so when things broke my first guess was that my XML was somehow wrong for adding a second provider - although the UI in InetMgr seemed happy with my addition. Symptoms of the break for me were "File Not Found" on the Operations and Application Management tabs - and the home page went to a Server Error in '/' Application that wouldn't display anything other than the custom error no matter what I tried.
So I removed my XML and the problem stayed. As part of my training was to be comparing web.config files at various points during the training I took my own medicine and fired up windiff. And there it was - the edit configuration option had added an attribute to my <configuration> element. Instead of just <configuration> on line 2, I had <configuration xmlns="http://schema.microsoft.com/.netConfiguration/v2.0">. Removing the extra text got my Central Administration site up and running again.
This is a known issue - KB 917238 - but in case you see these symptoms - take a look at your web.config.
Let me know if anyone out there is interested in authentication of Project Server 2007 with LDAP and I will blog my findings so far.
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