determine default browser setting in a WinUI app in Windows11

Question

I followed several hints on how to get the "default browser" in windows, but they all are how to read the registry path from Current.User: Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice

HOWEVER, I have both Chrome and Edge on my machine. When switching between the two as the default, I always get "ChromeHTML". So, this does not seem like it will work!

This happens to be for a .NET MAUI app

• Dai: Are you referring to the ProgId value? What do you see under HKEY_CLASSES_ROOT\ChromeHTML ?
• Simon Mourier: stackoverflow.com/a/76966324/403671
• bobwki: @Dai, whether Chrome or Edge is set as default, this shows info about Chrome.

Answer 1

This works on Windows 11:

internal static bool TryGetSystemDefaultBrowserPath(out string path)
{
 path = string.Empty;
 try
 {
 using var regDefault = Registry.CurrentUser.OpenSubKey(
 name: "Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\FileExts\\.htm\\UserChoice",
 writable: false);
 if (regDefault?.GetValue("ProgId") is not string { Length: > 0 } stringDefault)
 {
 return false;
 }
 using var regKey = Registry.ClassesRoot.OpenSubKey(
 name: stringDefault + "\\shell\\open\\command",
 writable: false);
 if (regKey?.GetValue(null) is not string raw ||
 string.IsNullOrWhiteSpace(raw))
 {
 return false;
 }
 var name = raw.Trim().Trim('"');
 var exeIndex = name.IndexOf(".exe", StringComparison.OrdinalIgnoreCase);
 if (exeIndex < 0)
 {
 return false;
 }
 name = name[..(exeIndex + 4)];
 path = name;
 return true;
 }
 catch
 {
 return false;
 }
}

• Andrew KeepCoding: @bobwki You've set the bounty after I posted this answer. Does that mean that this answer didn't solve your issue?
• bobwki: well, on my system it always returned "ChromeHTML", whether set to Chrome or Edge. So, no. I appreciated your answer, though, so I upvoted.
• Andrew KeepCoding: This method returns the "path" to the default browser. Can you check again?
• bobwki: I tried again today, and, maddeningly, when I changed default browser to Edge, and restarted Windows, and verified by using the Windows Search box to open my website, your call still returns CHROME -- C:\Program Files\Google\Chrome\Application\chrome.exe. Hard to believe...
• bobwki: EVEN MORE MADDENING -- I uninstalled Chrome. Now your code returns "false". "stringDefault" is set to "ChromeHTML", which leads to the next OpenSubKey to return NULL.