what's the problem? getting this error :Access blocked: Authorization Error xxxxxxxxx@gmail.com The OAuth client was not found.

[aivagrin]

ubuntu 24.04
Access blocked: Authorization Error

xxxxxxxxx@gmail.com
The OAuth client was not found.
If you are a developer of this app, see error details.
Error 401: invalid_client

[yulong127]

having this problem as well, any solution?

[revanthsaii]

The "Error 401: invalid_client" with "OAuth client was not found" is a common authentication issue in Gemini CLI. Here's the solution:

Root Cause

This happens when the OAuth credentials are not properly set up or the API key is invalid/expired.

Solutions (Try in Order):

Solution 1: Refresh API Key

1. Go to Google Cloud Console: https://console.cloud.google.com
2. Select your project
3. Go to Credentials > OAuth 2.0 Client IDs
4. Delete the existing OAuth client
5. Create a new OAuth 2.0 Client ID (Desktop app)
6. Download the JSON file

Solution 2: Clear OAuth Cache

The CLI caches OAuth tokens. Clear them:

Linux/Ubuntu:
rm -rf ~/.config/geminiacli

Or:
rm -rf ~/.geminiacli

MacOS:
rm -rf ~/Library/Application\ Support/geminiacli

Windows:
rmdir %APPDATA%\geminiacli /s

Solution 3: Re-authenticate

After clearing cache, run fresh login:
geminiacli auth

Then follow the browser OAuth flow.

Solution 4: Check Environment Variables

Make sure your API key is correctly set:

export GEMINI_API_KEY=your_actual_key

Verify it's set:
echo $GEMINI_API_KEY

Solution 5: Use API Key Method (Alternative)

Instead of OAuth, use direct API key:

1. Get API key from: https://ai.google.dev/
2. Set it:
   export GEMINI_API_KEY=your_key
3. Run without OAuth:
   geminiacli --use-api-key

Additional Troubleshooting:

• Update CLI to latest version:
  npm update -g @google/generative-ai-cli

• Check if OAuth client scope includes necessary permissions

• Ensure Ubuntu 24.04 has proper SSL certificates:
  sudo apt-get install ca-certificates

• Try with --debug flag to see detailed errors:
  geminiacli auth --debug

Let me know which solution works or if you see a specific error message with --debug flag!