I found a strange IIS error today which had to do with the configuration files for the application pools.

HTTP Error 500.19 - Internal Server Error
The requested page cannot be accessed because the related configuration data for the page is invalid.

 
 

...was the error I saw which further flagged this line of code...

<virtualDirectory path="/" physicalPath="C:\inetpub\wwwroot"
      userName="ourlan\tjaeschke" password=
      "[enc:AesProvider:mn8+xtHgy6HNa9Fvg9kv+OEoClrJ0HBhDn0OgR3vnuSg3y
      PFRmk11S3GpqEy9gr4:enc]" />

 
 

...in this file:

C:\inetpub\temp\appPools\DummyWebSite\DummyWebSite.config

 
 

I could make the error go away by doctoring the line of code like so:

<virtualDirectory path="/" physicalPath="C:\inetpub\wwwroot" />

 
 

So that I would not have to do this everytime IIS restarted, I just set the Identity for DefaultAppPool which had this problem (which wasn't even the pool dummywebsite was using) to ApplicationPoolIdentity and restarted IIS. What a weird problem. Did I just have the password for my account set wrong? I bet that was culprit.