Inquiry Regarding "Outdated Runtime" Warning for Azure Functions Using Custom Container

Question

Dear Azure Support Team,

We are currently using a custom-built Docker image with Azure Functions (Linux / Custom Container).
The base image specified in the Dockerfile is mcr.microsoft.com/azure-functions/python:4-pythonX.X-appservice, and we have confirmed that the internal runtime version is up to date.

However, the Azure Portal continues to display a warning stating that an "outdated runtime (e.g., 4.21.1.1)" is being used.
This warning does not appear for other Function Apps using the exact same Docker image, and there are no differences in App Settings or configuration.

Additionally, during the initial deployment of the affected Function App, the Docker image pull was interrupted, and the following log entries were recorded: Container pull image interrupted. Revert by terminate. Site container terminated during site startup.

After that, the same image was restarted and confirmed to be running successfully.
We suspect that this pull failure history may have been retained by the Azure host and could be the reason for the warning.

We would appreciate your guidance on the following points:

1. What information (e.g., image SHA, pull history, App configuration) is used to determine and display this warning?
2. Is it possible that a single pull failure or startup failure could cause the warning to persist?
3. Is there a way to resolve or clear the warning without recreating the Function App?

Thank you very much for your assistance.

Answer 1

As the warning no longer appears over time, we will proceed to close this case.