Solved: Site configuration property (Site.SiteConfig.LinuxFxVersion) for Flex Consumption sites is invalid

Error

You’ve encountered the error below when trying to upgrade the version of Node.js for your Linux Flex Consumption Function App (via Azure az CLI & Azure portal)

The following site configuration property (Site.SiteConfig.LinuxFxVersion) for Flex Consumption sites is invalid. Please remove or rename it before retrying.

Screenshot from the Azure portal after trying to update the stack settings:

Solution: Use the az cli

Run the following command from the terminal replacing [RESOURCE NAME] with the name of your Function App and [RESOURCE GROUP] with the name of the Resource Group:

az functionapp runtime config set --runtime-version 24 --name [RESOURCE NAME] --resource-group [RESOURCE GROUP]