Process.Start(url) fails

Had the same problem, solved without IE fallback.
This will make it behave more like just typing it in the 'Run' window:

Process.Start(new ProcessStartInfo("https://www.example.com") { UseShellExecute = true });

Note that I'm setting UseShellExecute = true

The default is supposed to be true on .Net Framework, and false on .Net Core
and UWP apps should not use this flag. see docs
(I was running on .Net Core)

Try using explorer.exe for the fileName explicitly.

As detailed in Process.Start(url) broken on Windows 8/Chrome - are there alternatives?

Process.Start("explorer.exe", url);