MVC 6 Web App hangs after publish RRS feed

  • Question

  • I just published an MVC 6 web app yesterday (rc1-update1) from Visual Studio and it worked completely fine. Then today I went to push an update to a new deployment slot and it seems to publish fine but when I try to hit the site it just hangs there and returns either a 500 or sometimes a 503. I enabled all logging and the only thing that came up were a bunch of repeated "Process '0' failed to start." errors from the HttpPlatformHandler.

    After much hair pulling I decided to try the simplest thing possible just to see if I could get anything to work. I created a brand new app service in the portal and made a new project that consists solely of the MVC 6 project template default site. Publishing this to the new app service yields exactly the same results.

    Has anyone else had this problem or know how to fix it? I'm at a total loss.

    • Edited by zparrish Tuesday, February 23, 2016 12:56 PM
    Tuesday, February 23, 2016 4:03 AM

All replies

  • In case it helps anyone else, I was able to figure out the problem. I checked the logs again after letting the app site for awhile and discovered the following error:

    Microsoft.AspNet.Server.Kestrel.Networking.UvException: Error -4091 EADDRINUSE address already in use

    So basically if you want to use deployment slots with an app using kestrel, then each one will have to be configured with a different port in the project.json file:

    "commands": {
        "web": "Microsoft.AspNet.Server.Kestrel --server.urls=http://localhost:5000"

    It seems less than ideal if your goal is to deploy to a staging slot for a quick sanity check before swapping as you have to know which ports are currently in use on which slot before publishing, but maybe it'll get fixed somehow in a future release.

    • Edited by zparrish Tuesday, February 23, 2016 1:35 PM
    • Proposed as answer by Ealsur Tuesday, February 23, 2016 2:25 PM
    Tuesday, February 23, 2016 1:34 PM