Static Web Apps: Managed Functions returning "Function host is not running"

Stuart Leeks 81

I have deployed a Static Web App with Managed Functions and whenever I call the /api endpoints, I get a 503 response with content "Function host is not running".

I've enabled App Insights integration, but all I see in the logs there is "A host error has occurred during startup operation 'faa622eb-6fcb-4948-9c19-0d03824f0547'."

How can I get more information on what is causing this issue so that I can resolve it?

SnehaAgrawal-MSFT 21,926 Reputation points

2022-01-04T08:43:44.47+00:00

Thanks! Could you please check on the configuration as API endpoints are available to the web app through the api route. and for managed functions
While the api route is fixed, you have control over the source code folder location of the managed functions app. You can change this location by editing the workflow YAML file located in your repository's .github/workflows folder.

For more details on Managed functions check this document link might be helpful: https://learn.microsoft.com/en-us/azure/static-web-apps/apis

Let us know.
Stuart Leeks 81 Reputation points

2022-01-04T08:48:01.997+00:00

I'm deploying via the Azure DevOps task rather than GitHub. Also, the deployment step succeeds, but I still get the "Function host is not running" message.

How can I get more details on why the Function App failed to start?
Tester, Joshua 1 Reputation point

2022-05-05T08:16:21.363+00:00

Just curious if you ever found a solution to this problem? I just ran in to it today and can find little to no help on how to resolve the error or what even causes it. I'm using .net 6 v4 azure function as well
Taylor Hutchison 56 Reputation points

2022-05-16T22:59:12.16+00:00

I was getting this too and I was able to fix it. I'm not exactly sure what's going on, but maybe this advice can help someone else.

I was deploying a static web app including functions written in .NET 6. Originally I was building the api myself in an Azure DevOps pipelines and selecting "skip api build" in the static web app deployment step using the "AzureStaticWebApp" task. However, letting the static web app deployment step do the build made it work.

I think this is because there is a build system called "Oryx" that runs during the deployment step and if it detects you are using .NET 6 it will set the Functions Runtime to ~4 and dotnet version to 6.0. You don't seem to be able to set these yourself like you would in a stand-alone Functions App.

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SnehaAgrawal-MSFT 21,926 Reputation points

2022-01-05T10:20:01.707+00:00

Thanks for reply! Which language you are using? Static Web Apps' managed function apps don't support all languages or language versions that Azure Functions supports. For managed functions the Azure Functions app must either be in Node.js 12, .NET Core 3.1, .NET 6.0, or Python 3.8.

You may refer to this article and step-by-step guides to troubleshooting deployment and other issues for your static web app.
You may use Application Insights to find runtime error messages.
Refer to Monitoring Azure Static Web Apps. Application Insights logs the full error message and stack trace generated by each error.

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Static Web Apps: Managed Functions returning "Function host is not running"

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