During development if you stop the iis and forgot to start it. And later on restart Skype it will take over port 80 / 443, which will later on cause us an Error 0x80070020 when we try to start the website from IIS manager console.

The error code 0x80070020 translates to ERROR_SHARING_VIOLATION (The process cannot access the file because it is being used by another process.)

This issue may occur if TCP port 80 and/or 443 is grabbed by a different service.

Solution is to close Skype, and start website and start Skype again.

This might happen with other software which want to take over these ports but being a windows developer Skype is most commonly the cause of this issue.