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Finance | Project Operations, Human Resources, ...
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HTTP Error 503. The service is unavailable, until visual studio loads the project

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Posted on by 21

Hi Experts,

I noticed that in my dev environment, I always get 503 error until I open a project under visual studio. Is it something related to IIS express which visual studio starts while loading the project. If yes, any solution which can fix this issue?

Note: The above issue is not related to services like IIS admin and the world wide web.

  • Ludwig Reinhard Profile Picture
    Microsoft Employee on at

    Hi Sachin,

    Is this related to D365FO?

    Best regards,

    Ludwig

  • Suggested answer
    Sukrut Parab Profile Picture
    71,741 Moderator on at
  • Christoph Thaler Profile Picture
    5,442 on at

    Hi Sachin Goyal, 

    if it is D365 I saw it in our environments in some rare cases in the past. In our cases it was related with IIS. Please check the AOS and application pool in IIS. If one of them is stopped the web site is not available.

  • Sergei Minozhenko Profile Picture
    23,099 on at

    Hi Sachin,

    Does it happen every time when you try to open a project or only when you just started VM? I noticed similar behavior but only after VM restart and looks like not all services are started at this point.

  • WillWU Profile Picture
    22,363 on at

    Hi goyalsachin6,

    When you open Visual Studio, the VM switches to use IIS Express instead of IIS, which means that IIS will stop and IIS Express will start. This also means that you cannot start IIS again because IIS Express is now using the port. 

    When you close VS, it will close IIS Express and restart IIS for you.

    And you could restart IIS Express by selecting Dynamics 365 > Restart IIS Express in Visual Studio.

  • goyalsachin6 Profile Picture
    21 on at

    Hi Sergei,

    Yes, This issue comes when you start the VM and try to access the application. I believe it supposed to use IIS which I checked is started but still application remain unavailable. however when you open visual studio which eventually starts IIS express it becomes avaialable and after that when you close the visual studio, your application again become unavailable.

    I also notice that in build/test box, application always remains available when you start the VM.

    There should be some difference in terms of settings for both types of VM which is causing this issue.

  • goyalsachin6 Profile Picture
    21 on at

    Yes Ludwig.

  • Andrew Huisman Profile Picture
    313 on at

    Did you ever get this resolved?  I have the exact same issue right now in my dev environment.  Only works if VS is open.

  • André Arnaud de Calavon Profile Picture
    307,786 Super User 2026 Season 2 on at

    Hi Andrew,

    I had the same issue last week on a demo machine which was also a DEV topology. We updated the machine with latest releases and removed one package. At that time, we had the same issue. After installing a new deployable package, the issue got resolved.

    Can you tell what might be changed when you run into this issue or is this a fresh VM?

  • Suggested answer
    Andrew Huisman Profile Picture
    313 on at

    André, thank you so much!  We applied the latest deployable package from the Dev branch to my environment and now it works the way it should!

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