"There was an error while performing this operation"

It turned out the website was using URL rewrite module which i was missing.

Downloaded web platform installer from MS and installed URL rewrite module.

http://www.microsoft.com/web/downloads/platform.aspx

Wish IIS errors were more informative than just "There was an error..."

I am running IIS 8.5 and I deployed my first Asp.Net Core 2.0 (Razor pages) site to the IIS Server (on Windows Server 2012 R2) that was running several Asp.Net Framework/Classic websites. This worked for me:

Install the .NET Core Windows Server Hosting bundle

https://docs.microsoft.com/en-us/aspnet/core/publishing/iis?tabs=aspnetcore2x#install-the-net-core-windows-server-hosting-bundle

I had this issue as well. Trying to run ASP.Net Core on IIS 10. All I needed to do was this:

Screen shot taken from: https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/development-time-iis-support?view=aspnetcore-2.1

It turned out the website was using URL rewrite module which i was missing.

This wasn't my problem and it was. I already had URL Rewriter installed, but after a Windows 10 upgrade IIS wasn't aware of it. A simple repair on Control Panel => Programs and Features => IIS URL Rewrite Module 2 and it was working again.