Today, when I started my first ISAPI development and testing with Delphi for Habari Client message broker libraries, a fresh installation of Internet Information Server 7.5 (IIS Express) failed to start.
Launching with the debug parameter /trace:e gave this cryptic message:
Failed while trying to preload CLR version v4.0. hr = 8007000d Failed to initalize the W3WP_HOST hr = 8007000d Process Model Shutdown called Failed to start 'HostedWASStart'. Error = 28152744 HostableWebCore activation failed.
The “Failed while trying to preload CLR version v4.0” was the helpful hint. The reason of the startup error was simply a missing .NET 4.0 framework on the machine. To fix it, this line in C:\Users\Documents\IISExpress\config\applicationhost.config
<applicationDefaults applicationPool="Clr4IntegratedAppPool" />
had to be changed to
<applicationDefaults applicationPool="Clr2IntegratedAppPool" />
to switch to .NET framework 2.