Found in

• Nightly 109.0a1

Affected versions

• Nightly 109.0a1

Tested platforms

• Affected platforms: all
• Unaffected platforms:

Preconditions

• Opera/Vivaldi are installed(stable version from Ubuntu apps or from the following link: https://www.opera.com/download, I downloaded .deb file) and has user data to import:

• browsing history
• saved bookmarks
• saved Logins and Passwords
• search bar history
• cookies

• Create an user.js file with the following prefs:
  user_pref("browser.migrate.opera.enabled", true);
  user_pref("browser.migrate.vivaldi.enabled",true);
• Remove the profiles folder from:

• MacOS: Library\Application Support\Firefox
• Windows: %appdata%\Mozilla
• Ubuntu: home/user/.mozilla

Steps to reproduce

1. Open Fx profile manager from terminal using -p -migration command
2. Create a new profile.
3. Go to profiles folder and paste user.js to the new profile created above
4. Open Firefox with the profile created at step 2

Expected result

• Opera and Vivaldi browsers should be available on the first run migration

Actual result

• Opera, Vivaldi browsers are missing from the first run migration

Regression range

• Not a regression. New feature implementation

Additional notes

• Chrome browser is listed.

So I think I know what's going on here: when the startup migration dialog appears, we're not actually connected yet to the user's default profile (since the startup migration can be used to do a pave-over import from another Firefox), and that ephemeral profile that it connects to has the default prefs set. This means that setting the browser.migrate.opera.enabled or browser.migrate.vivaldi.enabled prefs will have no effect, since those pref flips will be set on the default profile, and not the "ephemeral" profile that's connected to at startup migration.

So the overall solution is to enable the prefs by default, but since we're not exactly ready to do that, we can fix this by only turning on these migrators by default in Nightly.

Nolan, you can turn these prefs on in Nightly only by using these build-time "ifdef" conditions, like this: https://searchfox.org/mozilla-central/rev/a44deb21744de6269329b05461c55488a147f95e/browser/app/profile/firefox.js#129-139

so we'd want something like this:

#ifdef NIGHTLY_BUILD
pref("browser.migrate.opera.enabled", true);
pref("browser.migrate.opera-gx.enabled", true);
pref("browser.migrate.vivaldi.enabled", true);
#else
pref("browser.migrate.opera.enabled", false);
pref("browser.migrate.opera-gx.enabled", false);
pref("browser.migrate.vivaldi.enabled", false);
#endif

Note that I tossed Opera GX in there too, since this will surely affect it as well.

https://hg.mozilla.org/mozilla-central/rev/640b3c21bfb9

The patch landed in nightly and beta is affected.
:nolan.ishii, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox109 to wontfix.

For more information, please visit auto_nag documentation.

No, this is not important enough to require an uplift. We'll continue to hold this on Nightly until we get a sufficiently green sign-off from QA.

We verified the fix using Nightly 110.a01 (20-12-2022) on Windows 10 x64, Ubuntu 18.04 x64, macOS 11 and Windows 10 ARM. The issue is not reproducing anymore. Opera, Opera GX and Vivaldi browsers are available on the first run migration.