Launcher r5334 - Could not authenticate to Plutonium (401) before login screen

[croartss]

Hello,

I am experiencing a persistent authentication issue with the Plutonium launcher.

System Information
Operating System: Windows 11 Pro 25H2
Build: 26200.8737
Launcher Revision: r5334
Game: Call of Duty: Black Ops II (Steam)
Issue

When I launch Plutonium, the launcher opens a black window for a few seconds and then immediately displays the following error:

Could not authenticate to Plutonium: non-success status code: 401

The login page never appears.

What I have already tried
Downloaded the launcher from the official website.
Deleted the entire %LOCALAPPDATA%\Plutonium folder.
Deleted config.json and info.json.
Reinstalled the launcher multiple times.
Verified that Microsoft Edge WebView2 Runtime is installed.
Verified that Black Ops II is correctly installed through Steam.

Verified the game path:

C:\Program Files (x86)\Steam\steamapps\common\Call of Duty Black Ops II
Confirmed that the Plutonium website and forum are accessible.
Confirmed that my email address is verified.
Tested with two different Plutonium accounts (same result).
Windows Defender is the only antivirus installed.
No VPN or proxy is being used.
Ran the launcher as Administrator.
Launched plutonium-launcher-win32.exe directly from the bin folder (same result).
The console log file remains empty.
Windows Event Viewer does not show any crash related to Plutonium.
Additional Information

The launcher window stays completely black before the 401 error appears.

It never reaches the login screen.

Since the exact same issue occurs with a brand-new account, I don't believe the problem is related to my account.

Could this be a launcher issue with Windows 11 25H2 or revision r5334?

Any help would be greatly appreciated.

Thank you.

[Hadi77KSA]

The error you’re showing is from running the bootstrapper, not the launcher. Run the launcher, sign in, make sure the game path is set correctly, and start the game through it.

[croartss]

Hadi77KSA Hi,

Thank you for your reply.

I also tested plutonium-launcher-win32.exe directly from %LOCALAPPDATA%\Plutonium\bin, not only the bootstrapper.

The result is exactly the same:

the launcher opens a black window,
the login page never appears,
after a few seconds it shows:

Could not authenticate to Plutonium: non-success status code: 401

I have also:

deleted %LOCALAPPDATA%\Plutonium,
reinstalled the launcher,
tested with two different Plutonium accounts,
verified the game path,
verified WebView2,
and the issue is still exactly the same.

Is there any debug log or command line option I can use to investigate why the launcher cannot reach the login screen?

[Hadi77KSA]

I highly suspect you’re not opening the launcher. Please show a video of you starting Plutonium from plutonium.exe. It would be better if you do so in the Plutonium Discord server for faster responses.