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1. If you are working in Visual Stuido 2019, Stop the Application and Clean the Solution.
2. If needed, close Visual Studio 2019 and restart it, load the project you are working with.
3. Clear or hard refresh the browser if you are working with Google Chrome update the Browser
4. Make sure the url in the method directive in the embended Form starts with a slash e.g.
method = "/myfunction"
5. Test again.