When you access the site for PSIfusion, you may receive the following error:
HTTP Error 500.19 - Internal Server Error - The requested page cannot be accessed because the related configuration data for the page is invalid
It may also list "Config Source"
This usually indicates that ASP.NET was not installed, or it installed incorrectly. Go back to the IIS Components for Programs and Features and ensure ASP.NET is deployed. Once corrected, cycle the IIS webserver and re-try PSIfusion.
Problem 2: HTTP 500.19 - Internal Server Error
The Config Error may list: The configuration section 'protocolMapping' cannot be read because it is missing a section declaration
Solution 2: The .NET CLR Version is most likely set incorrectly on the App Pool. Go into IIS > Application Pools and verify that the pool for the Fusion site is using .NET CLR v4 and not v2