AZFD0013: The configured runtime does not match the worker runtime metadata found in the deployed function app artifacts

This event occurs when a function app has a FUNCTIONS_WORKER_RUNTIME setting specifying a language stack, but a payload for a different stack is deployed to it.

Event description

The FUNCTIONS_WORKER_RUNTIME application setting indicates the language or language stack on which the function app runs, such as python. For more information on valid values, see the FUNCTIONS_WORKER_RUNTIME reference. The deployed application must correspond with the provided value. If there is a mismatch, it means that either the value of FUNCTIONS_WORKER_RUNTIME is incorrect, or that an unexpected payload was deployed to the application.

This event may appear for apps that were previously using inconsistent and undefined behavior to continue running while in a mismatch state. Follow the instructions in this article to resolve the event for these applications. Doing so allows these apps to take advantage of performance enhancements and ensure that they can continue to operate as expected.

.NET apps undergoing a migration from the in-process model to the isolated worker may encounter this event temporarily during that process. When FUNCTIONS_WORKER_RUNTIME is updated to "dotnet-isolated", but the application is still using an in-process model payload, this event may appear until the migration is completed. See the migration guidance for instructions on using deployment slots to prevent this event from appearing in your production environment.

How to resolve the event

The event message indicates the current value of FUNCTIONS_WORKER_RUNTIME and the detected runtime metadata from the app payload. The values must be aligned, either by deploying an application of the appropriate type or by updating the value of FUNCTIONS_WORKER_RUNTIME to match.

For most applications, the correct resolution is to update the value of FUNCTIONS_WORKER_RUNTIME. To do so, on your function app in Azure, set the FUNCTIONS_WORKER_RUNTIME application setting to the expected value for your application payload. When running locally in the Azure Functions Core Tools, you should also add FUNCTIONS_WORKER_RUNTIME to the local.settings.json file.

For apps following a migration guide, see that guide for relevant instructions. Migrating .NET applications to the isolated worker model involves first setting FUNCTIONS_WORKER_RUNTIME to "dotnet-isolated" before deploying the updated application payload, and this event may appear temporarily between those steps.

When to suppress the event

This event shouldn't be suppressed.