Awesome, that fixed it for me too, I used default="cmd /c start %1" so it just opens a new tab in existing window. It was so annoying.

Most here are using a Microsoft product, Internet Explorer 11, Edge just isn't ready yet.
I also did an in place update.

Same problem for me, it's really annoying. I've checked Default Apps, they are all set correctly, if I change the default app to Microsoft Edge, it just opens, if it's Internet Explorer it prompts...