“Current thread must be set to single thread apartment (STA)” error in copy string to clipboard

Question

I have tried code from How to copy data to clipboard in C#:

Clipboard.SetText(\"Test!\");

And I get this error:

Curr

Answer 1

Make sure thread that runs the code is marked with [STAThread] attribute. For WinForm and console based apps it is generally Main method

Put [STAThread] above your main method:

[STAThread]
static void Main()
{
}

For WinForms it is usually in generated Main.cs file that you can edit if necessary (it will not be re-generated on changes). For console it's were you define the Main.

If you can't control the thread (i.e. you are writing a library or main app is locked by some reason) you can instead run code that accesses clipboard on specially configured thread (.SetApartmentState(ApartmentState.STA)) as shown in another answer.