Failed to start application '/LM/W3SVC/4/ROOT', ErrorCode '0x8000ffff' on producttion server, but works OK on test server

Clemens Linders 21 Reputation points


This is a problem installing a Blazor application created in .Net 5, on a production server, where as on a test server there is no problem.

We have a production server (Windows 2016) and I have a test server on a VMWare image: a Windows Server 2016 DataCentre.

I have a Blazor server side application that is developed on .Net 5.

If I deploy this on the test server. It works, no problem.

If I deploy this on our production server I get in the vent viewer the error: Failed to start application '/LM/W3SVC/4/ROOT', ErrorCode '0x8000ffff'.

On the internet it was suggested that I needed to install some server roles.

On our production server I don't want to simply add a lot of roles and see what happens, so I removed roles on my test server so that the roles regarding IIS were the same.

After remove some roles on the test server, the blazor application still works on my test server.

In order to get a blazor server-side application working I need to install the dotnet-hosting bundle.

On my test server I installed dotnet-hosting-3.1.19-win and on the server I installed dotnet-hosting-6.0.2-win.

So on the test server I removed the 3.1.19 version and installed the 6.0.2 version.

After all these changes the application on my test server keeps functioning.

On the internet I found that (for this error) you could alter the web.config file.
I can understand this, if the problem would be that I could run the application from visual studio but not from a server.

But it is working on my test server, so I cannot imagine that I would need to change the web.config. Botth are Windows 2016 servers.

I checked the web.config and there are no absolute paths mentioned in this config file.

I compared on both systems the IIS setup. Both have (for the application pools) Enable 32-bit Applications set to false.
The user and user rights are set OK on both machines.

I am running out of ideas, I hope someone can help me.

PS: the errors reported by the web browser and the event viewer are different.
If I simple open the application from IIS, the web browser (on both systems this is FireFox) reports:

HTTP Error 500.31 - ANCM Failed to Find Native Dependencies

Common solutions to this issue:
The specified version of Microsoft.NetCore.App or Microsoft.AspNetCore.App was not found.
Troubleshooting steps:
• Check the system event log for error messages
• Enable logging the application process' stdout messages
• Attach a debugger to the application process and inspect

For more information visit:

Kind regards,

Clemens Linders

Internet Information Services
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  1. Bruce ( 44,811 Reputation points

    you should check which versions of .net core runtimes are installed on the production server:

    dotnet --list-runtimes

    the 3.1 hosting module installs core 3.1, the 6 hosting module installs net 6, but you application is net5. at some point you probably installed net 5 on the test server. you probably will need to install net 5 runtime on the production server.

    note: net 5 support ends 5/8/2022, so you should upgrade to 6 in the next 3 months.

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  2. Clemens Linders 21 Reputation points

    Hi Bruce,

    I updated the solution from .Net 5 to .Net 6

    I installed the complete .Net 6 runtime (dot-net-runtime-6.0.2-win-x64.exe + aspnetcore-runtime-6.02-win-x64.exe and dotnet-hosting-6.0.2-win.exe) on both my test server and production server.

    Again on my test server everything is OK, when I click Browse in IIS it opens the site/apppplication in my browser.

    On the production server something has changed.
    I no longer get an error. Not in the browser and not in the event viewer.

    But............ when I click open site in IIS, it opens a browser and the page stays empty, complete white.

    As mentioned the page is complete white no error no nothing???

    PS: I did restart IIS, but this made no difference.

    If I open another browser (on the production server) and go to: (the application is on port 12004), than also on this browser I get a blanc/white page.

    I am running out of ideas. I hope you have an idea?

    Kind regards,

    Clemens Linders

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