Troubleshooting

When troubleshooting errors in Eto.Forms, be sure to check the inner exception(s). You can do this by adding $exception.GetBaseException() to the watch window after an exception is thrown.

WPF doesn’t run, but other platforms do

Exception thrown: Eto.HandlerInvalidException: Could not create instance of type Eto.Forms.IForm
Base exception: InvalidOperationException: The calling thread must be STA, because many UI components require this.
Solution: Add [STAThread] to your Main() method. The project templates already include it.

A Mac app built on Windows doesn’t run on a Mac

Windows file systems don’t keep the executable bit, so it’s lost on the executable inside the .app bundle. For testing, you can fix it on the Mac with:

chmod +x MyApp.app/Contents/MacOS/MyApp
xattr -c MyApp.app

To give your app to other people, sign and notarize it instead.

A Mac app doesn’t run from the command line

You can’t start an .app bundle with dotnet MyApp.dll. Use dotnet run, open MyApp.app, or run the executable inside the bundle directly:

./MyApp.app/Contents/MacOS/MyApp

GTK doesn’t run on Windows or macOS

GTK isn’t included with Windows or macOS. See Running GTK on Windows or macOS.