Whilst setting up a site on a 64bit server running IIS7.5, I was stumped with this error in the event log for a few hours “Could not load all ISAPI filters for site ###. Therefore site startup aborted.” A quick search of Google resulted in a number of fixes, none of which helped.
My colleague and I eventually discovered that the error was caused by a setting the advanced settings section of the application pool. To fix this yourself complete the following steps:
- Open IIS and navigate to the application pool in question.
- Right click and select Advanced Settings…
- In the (General) section locate “Enable 32-Bit Applications” and set this value to True
- Click OK
- Restart the web site