Issues with Delta CRL Publishing to IIS

I have an Enterprise CA that publishes its CRL to an IIS (7.5) website. The CA adds a plus (+) character to the file name for the Delta CRL.

In order for IIS to show this plus sign properly you need to allow double escaping. You can do this with powershell:

Set-WebConfiguration -Filter system.webServer/security/requestFiltering -PSPath ‘IIS:\sites\My Web Site’ -Value @{allowDoubleEscaping=$true}

You may need to import the IIS module first with:

Import-Module Webadministration