Accessing a SharePoint server from outside a network with a Forefront TMG.
The following 2 scenarios can give you an Internal Server Error
- View properties on document
- Editing a list view
Full error text:
Error Code: 500 Internal Server Error. The request was rejected by the HTTP filter. Contact the server administrator. (12217)
The reason why this happens is that the HTTP filter in Forefront has a URL protection mechanism wich will block URLs containing escaped characters after normalization.
To fix this:
- Open the properties of the firewall policy.
- Under the Traffic tab. Click Filtering
- Uncheck Verify normalization in the URL Protection section
Verify normalization will block URLs containing escaped characters after normalization.