lync-2010-error-while-installing-webcomponents-msi

 http://techsps.wordpress.com/2010/12/22/lync-2010-error-while-installing-webcomponents-msi/

When configuring certificates for a lync 2010 environment, I noticed that I made a typo. Failing to correct the problem via the topology builder, I had to uninstall the lync software. After correcting my typo, the installation failed to install. This was the error I got:

 

After doing some digging I noticed also an event in the eventviewer:

 

Opening the log file as mentioned in the event, it turned out I had something to do with an duplicate entry in the applicationhost.config.

 

As stated in the error it had something to do with a duplicate entry at line 421. Opening the applicationhost.config learned that line 421 didn’t had anything to do with lync. The trick was to find OCSAuthHelperModule:

<add name="OCSAuthHelperModule" image="C:\Windows\Assembly\GAC_64\Microsoft.Rtc.Server.WebInfrastructure\4.0.0.0__31bf3856ad364e35\Microsoft.Rtc.Server.WebInfrastructure.dll" preCondition="integratedMode,runtimeVersionv2.0,bitness64" />

After deleting this entry, the installation went perfect!