Gemini Error 1099 shows up during the Analysis phase when you use Gemini Pro or Thinking mode. You submit a prompt, it starts analyzing, and then returns the error: “Something went wrong (1099).” Switching prompts does nothing. Starting a new chat does nothing. The error follows your session.
This is not a browser bug. It is a backend session-state conflict tied specifically to the Pro and Thinking models. Everything below targets that root cause directly.
What Is Gemini Error 1099 and Why It Keeps Happening
When Gemini Pro processes a prompt, it runs an analysis step before generating the response. Error 1099 fires when that analysis step hits a conflict in your session state on Google’s servers. Because the conflict lives server-side, clearing your browser cache or reloading the page will not fix it. The session token itself needs to be reset, or you need to bypass the affected session entirely.
This is different from Gemini Error 13, which blocks text input at the account level. Error 1099 specifically locks the Pro and Thinking models mid-response.
Fix 1: Switch to Gemini Flash
The fastest way to get unblocked is to stop using Pro or Thinking mode temporarily.
- Open your Gemini chat.
- Click the model selector at the top of the chat window.
- Switch from Gemini Pro or Gemini 2.5 Thinking to Gemini Flash.
- Resubmit your prompt.
Flash does not go through the same analysis pipeline, so it bypasses the 1099 error in most cases. During a broad backend outage, Flash can also be affected alongside Pro and Thinking. The June 10, 2026 outage saw error 1076 and 1099 firing together across Flash, Pro, and Thinking on both web and app. If Flash fails as well, the issue is a wider Google backend problem rather than a session conflict tied to your account.
Fix 2: Hard Refresh to Clear the Session Token
A regular page refresh keeps your current session token intact. A hard refresh forces the browser to drop it and request a new one from Google’s servers.
- On Windows: Press Ctrl + F5 or Ctrl + Shift + R
- On Mac: Press Cmd + Shift + R
After the hard refresh, open a brand-new chat rather than continuing an existing one. Starting fresh with a new session token is what matters here, not just reloading the same chat window.
Fix 3: Open Gemini in an Incognito Window
Incognito mode creates a completely isolated session with no cookies, extensions, or cached session data from your main browser profile.
- Open a new incognito or private browsing window.
- Chrome: Ctrl + Shift + N (Windows) / Cmd + Shift + N (Mac)
- Firefox: Ctrl + Shift + P / Cmd + Shift + P
- Edge: Ctrl + Shift + N / Cmd + Shift + N
- Go to gemini.google.com and sign in.
- Start a new chat in Pro mode and test your prompt.
If Gemini Pro works in incognito but not in your regular browser, a browser extension is interfering with your session. Disable extensions one by one to identify the cause.
Fix 4: Sign In With a Different Google Account
If the session conflict is tied to your specific account, switching to another Google account immediately bypasses it. This is the most reliable temporary workaround while your main account session gets resolved.
- Click your profile icon in the top-right corner of Gemini.
- Select Add another account or switch to an existing secondary account.
- Open a new chat in Pro mode under that account.
If the error does not appear on the secondary account, the conflict is isolated to your primary account’s session data on Google’s backend.
Fix 5: Submit a Feedback Report With System Logs
This is not a generic “contact support” suggestion. Submitting feedback with system logs attached is how you route the error directly to Google’s engineering team for investigation. Without the logs, they cannot trace the specific session state that caused the 1099.
- Open the Gemini web app on the affected account.
- Click Help in the bottom-left corner.
- Select Send feedback.
- In the description box, paste this exactly: “Constantly receiving ‘Something went wrong (1099)’ during the Analysis phase of prompts. Issue persists across multiple prompts and new chats. Suspected backend session conflict in Gemini Pro/Thinking mode.”
- Check the box labeled Include screenshots and system logs. This step is critical. The logs contain the session data engineers need to locate and fix the conflict.
- Click Send.
You will not receive a direct reply, but the logs route to the team responsible for the 1099 error. After submitting, monitor whether the error clears on its own over the next 24 to 48 hours.
Why This Happens More in Pro and Thinking Mode
Gemini Flash runs a simpler, faster pipeline. Pro and Thinking models run an extended analysis step that involves more server-side coordination. That additional processing creates more opportunities for a session state conflict to occur, especially during periods of high backend load or after a recent model update. Google has acknowledged this as a known issue affecting Pro and Thinking mode specifically.
Gemini Notebooks run the same extended analysis pipeline, which makes them equally vulnerable to the 1099 error. If you hit error 1099 inside a Notebook, switch to a standard chat outside the Notebook as a first step.
If you hit Gemini usage limits around the same time, the two issues can look similar but have different causes. A usage limit locks you out with a specific quota message. Error 1099 returns mid-response during the analysis step and does not mention quotas.
