Quick Answer
The error message “Failed to sign in. This client is no longer supported for Gemini Code Assist for individuals” means your IDE extension (Cloud Code for VS Code or IntelliJ) is outdated, or you are attempting to use a deprecated personal tier. To fix this, update your IDE extension to the latest version, sign out of your Google account within the IDE, and re-authenticate. If the personal tier is fully sunset, you must transition to a Google Workspace or Google Cloud Enterprise billing account.
Development tools evolve rapidly. Google frequently updates the backend architecture for Gemini Code Assist (formerly Duet AI) to improve latency, context windows, and security. When this happens, legacy authentication flows in older IDE plugins are deliberately blocked to prevent misaligned API calls and degraded performance.
Root Causes for Deprecation Errors
Unlike standard API network issues like Gemini Error 1095, this is an explicit block by the identity provider. Google is recognizing your client, reading its version number, and rejecting the handshake.
- Outdated Plugin: The Google Cloud Code extension in VS Code or JetBrains is running an old build.
- Tier Retirement: Google may have deprecated the specific “individual/free” access tier you initially signed up for, requiring a migration to a paid or enterprise SKU.
- Corrupted OAuth Tokens: The local token stored in your IDE’s secure storage has expired, but the IDE is failing to silently refresh it, resulting in a generic “unsupported client” message.
Update and Re-Authentication Pipeline
Fixing this is generally straightforward and requires resetting the local state of your developer environment.
| IDE Platform | Steps to Resolve | Verification |
|---|---|---|
| Visual Studio Code | Extensions > Cloud Code > Update. Then, use Command Palette: “Cloud Code: Sign Out”, then Sign In again. | Status bar shows “Gemini: Active”. |
| IntelliJ IDEA / JetBrains | Settings > Plugins > Update Cloud Code. Restart IDE. Invalidate Caches if necessary. | Gemini tool window loads chat. |
| Billing/Account Issue | Ensure the Google Account logged in has active Gemini Code Assist licenses assigned via Workspace. | No “Tier Deprecated” popups. |
Enterprise Considerations
If you have followed the steps above and still face rejection, it is highly likely the service tier attached to your personal @gmail.com account is no longer supported for this specific product iteration. You will need to link your IDE to a corporate Google Cloud Project with active billing, similar to resolving Error 1100 for API access.
TL;DR
The “client no longer supported” error for Gemini Code Assist requires immediate action on your IDE. Force an update of the Google Cloud Code extension, sign out completely, and sign back in. If the issue persists, your personal account tier has been sunset, and you must migrate to a supported Google Workspace or GCP billing account.
