title: Changing the target framework in an Azure web app
body: <p>I would like to publish an ASP.NET Core 2.1 website to Azure using an Azure Web App to host it. When creating the Azure Web App on the Azure portal, one of the settings is "Runtime Stack". In this case I would set it to ".NET Core 2.1" to match the framework my code is currently using. However once the web app is created, I do not see an option to edit this setting anywhere on the Azure portal, so how would I change it if necessary in the future? </p>
  
  <p>For instance, if I were to later update my application code to use ASP.NET Core 2.2, how would I change the runtime stack of the Azure web app to ".NET Core 2.2"? Is there a setting to edit this in some area of the Azure portal? Or does the Azure web app look at the code (possibly the .csproj file), and automatically update the target framework internally, thus ignoring any settings anyway? Or would I need to delete the web app and create a new one with the correct settings? (If I would need to delete the web app and create a new one, is there some recommended approach to plan for this situation and reduce downtime? Would it be possible to update the staging slot to a newer runtime stack from the production slot, and then do a swap?)</p>