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If you see “Failed to Fetch” or “Unable to connect to BrowserOS agent”, your agent has been killed.
Failed to fetch error

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Fix It

1

Go to Settings → MCP Server and click Restart

Open Settings from the sidebar, scroll to the MCP Server section, and click Restart. Wait a couple of minutes.
Click Restart in MCP Server Settings
2

If restart doesn't work, force quit the browser

Right-click BrowserOS in the Dock → Quit, then reopen the app.

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Still Not Working?

The agent runs on port 9100 by default. If another application is using this port, BrowserOS cannot start the agent.
Find the process:
lsof -i :9100
Kill it (replace PID with the process ID from above):
kill -9 PID
Then restart BrowserOS.
Some firewalls may block local connections. Make sure your firewall allows connections to 127.0.0.1:9100.Windows users: Antivirus software sometimes triggers a false positive. Try temporarily disabling your antivirus and restarting BrowserOS.

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