You might have had this similar error when trying to run a web application in Visual Studio. I had this error in VS 2019 Enterprise edition.
Let us discuss a scenario, how I ended up with this error. I was trying to setup my development environment. Cloned the project and started the project without debugging. This is when this pop up came.
I remembered that I had saved the project files in OneDrive. Also, the IIS configuration files are saved in Documents that synchronizes with the OneDrive.
The problem was the OneDrive sync was paused. To fix this I resumed the OneDrive and started the project again. It worked for me.
Before this error, I had gotten one more pop up to start the VS in Admin mode because it cannot read the configuration file.