IIS express: Cannot add duplicate collection entry of type 'add' with unique key attribute 'name' set to

Question

In Visual studio, Solution->Web.Project->Properties->Web, I have changed my Project Url from http://localhost:51123/ to http://localhost:51123/NewProj

Answer 1

You may find that after upgrading to the latest windows 10 service pack June 2017, this issue is because certain nodes seem to now appear under the root config (machine.config). I removed my duplicates from web.config and it all worked again.