Azure Function app not starting using .NET 8 Isolated in China North 3 region about azure-functions-dotnet-worker HOT 7 CLOSED

@pilarodriguez you should be able to create a ticket via the portal using the "Support + Troubleshooting" tab in your Function App

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@pilarodriguez

1. What specific error are you getting? Do you see any errors in your app insights tables?
2. Did you try the "Diagnose and solve problems" blade in azure portal to see if you can find more information about the failure?
3. If you try another deployment method, the app works?

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1. I don't get any errors. Application Insights is empty.
2. "Diagnose and solve problems" blade is disabled. That feature is not available in Azure China portal
3. I've tried deploying with yaml using AzureFunctionApp task and AzureRmWebAppDeployment. I get the same result with both

We are using durable functions. When the function app is started, it should create some tables and blobs that are used internally by the durable functions. But those are not created. It looks like the function is not starting at all

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Regerding the issue with the ".NET version" setting

This finding applies to both web applications and functions running on Windows.

A recent configuration quirk has emerged with the setup of .NET applications in China, specifically affecting the managedRuntimeVersion in the applicationhost.config file. This setting is critical for dictating the .NET Framework version an application uses, especially important for legacy ASP.NET applications not targeting .NET Core or the newer unified .NET platform.

Key Points:
ASP.NET V3.5 uses "v2.0".
Post-ASP.NET V3.5 applications (including .NET 6/7) default to "v4.0".
Anomaly in China: For .NET 8 applications, the managedRuntimeVersion is mistakenly set to "v8.0", a non-existent version causing IIS to fail with event id 2294 (The worker process failed to pre-load .Net Runtime version).

Implications and Workarounds:
This configuration error, specific to China, prevents IIS from starting properly for .NET 8 applications due to the unrecognized runtime version. Interestingly, this issue doesn't affect newer .NET platforms as managedRuntimeVersion isn’t used there.

A workaround involves setting an earlier .NET version (like .NET 6 or 7) for deployments in China to bypass the startup error. Meanwhile, in regions like Sweden Central, setting managedRuntimeVersion to v4.0 for .NET 8 applications avoids this issue entirely, indicating a region-specific bug rather than a broader compatibility problem.
.NET 8 runtime is installed in China and web applications and functions seems to run fine using that version.

Conclusion:
This incident highlights the critical role of correct configuration settings and how regional differences can impact the deployment of .NET applications. Addressing this bug is essential for seamless application performance across all regions, with a temporary shift to earlier .NET versions serving as a viable stopgap for those affected.

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@pilarodriguez This may need deeper investigation. Would you be able to create a support ticket for this?

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@kshyju Where should I create the support ticket?

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Please open a ticket as suggested and the team will be happy to investigate.

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