“Unable to launch the IIS Express Web server.” in Visual Studio

Question

I attempted to run my web service through visual studio. I faced an issue like :

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Microsoft Visual Studio
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Answer 1

The easiest first pass at this without getting into the command console is to just shut down all applications (including VS), then launch VS by itself and try it again. There is likely another application like your browser causing the conflict. In my case Chrome caused it and was solved when shutting everything down and restarting VS. I opened Chrome again and everything was fine.

The netstat stuff above is useful, but to me that's only if you can't do what I'm suggesting.

Answer 2

I ran into this problem in Visual Studio 2019 today and spent 3 hours before finally figuring out the problem. Visual Studio uses 2 files to track the SSL port number, so you have to fix both and you have to fix both while Visual Studio is closed. The two files are the applicationhost.config file that is in the .vs\???\config folder of your solution; and also the .csproj.user folder of your web project. Edit both files and removing the offending configs. Maybe even just delete both files. Then re-open your app in Visual Studio. Good luck!

Answer 3

I had the same problem today, and nothing I found on the internet worked. I have been using port 2057 for years, but suddenly it didn't work any more. Changing it to another low number like 2058 gave same error message, but when I changed it to 20057, everything worked again. Maybe something changed with the way the lower port numbers are handled.