The file could not be loaded into the Web Forms designer

You are attempting to open a file in the Web Forms designer that cannot be rendered correctly in the designer. This error occurs most commonly when you are working with a file that was originally created as a code-behind Web Forms page outside of Visual Studio. For more information about troubleshooting designer rendering issues, see Troubleshooting Design View Rendering.

See Also

Other Resources

Troubleshooting Design View Rendering

Design View, Web Page Designer