Title: Antigravity IDE Google OAuth Login Fails with HTTP ERROR 431

Google Antigravity
1

Hello Google Antigravity Team,

I am unable to complete the Google sign-in process in Antigravity IDE.

After clicking “Continue with Google”, the Google authentication completes successfully. However, when the browser redirects back to the local OAuth callback server, the following error occurs:

HTTP ERROR 431 – This page isn’t working

Callback URL: http:/localhost:56180/oauth-callback

Environment:

OS: Windows 11

Application: Google Antigravity IDE

Browser: Google Chrome

Google Account: Personal Gmail account

The Google authentication itself works correctly, but the localhost OAuth callback fails with HTTP 431, preventing Antigravity IDE from completing the login process.

I have attached screenshots showing:

Antigravity IDE login screen

Google authentication confirmation

HTTP ERROR 431 on localhost OAuth callback

Please investigate this OAuth callback issue.

Thank you.

2

Hi @Washim_Reja,

Could you please follow these steps:

    1. Clear localhost Cookies in Google Chrome (Direct Fix):

      • On the HTTP 431 error page in Chrome, press F12 to open DevTools.
      • Select the Application tab at the top.
      • In the left panel, expand Storage > Cookies.
      • Right-click http://localhost and click Clear.
      • Return to Antigravity IDE and click “Continue with Google” again.

    2. Authenticate in Chrome Incognito Window:

      • If you prefer not to clear your development cookies, copy the sign-in URL from Antigravity and open it in a Chrome Incognito Window (Ctrl + Shift + N), where no prior localhost cookies exist.

    3. Use CLI Manual Authentication (Bypasses Local Callback Server):

      • Open PowerShell or Command Prompt and run:

        agy auth login --no-browser

      • Open the generated link in your browser, complete Google authentication, and copy/paste the authorization code back into the terminal.

Let me know after you tried is the issue resolves or not?