Enable Always On when running on dedicated App Service Plan

Azure Functions can run on either a Consumption Plan, Premium Plan, or a dedicated (App Service) Plan. If you run in a dedicated mode, you need to turn on the Always On setting for your Function App to run properly. The Function runtime will go idle after a few minutes of inactivity, so only HTTP triggers will actually "wake up" your functions. This is similar to how WebJobs must have Always On enabled.

When running in a Consumption Plan or Premium Plan you should not enable Always On. On a Consumption plan the platform activates function apps automatically and on a Premium plan the platform keeps your desired number of pre-warmed instances always on automatically.

• To determine the hosting plan of an existing application see our documentation
• For more information about Always On see our documentation

Warning:

Enabling Always On on a Premium Plan will cause unnecessary scale out of your plan and generate a number of 503 responses.