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Fantommind Docs

Troubleshooting

import { Aside } from ‘@astrojs/starlight/components’;

License issues

Section titled “License issues”

”License validation failed” at startup

Section titled “”License validation failed” at startup”

Causes:

  • No internet connection (Fantommind requires online validation at boot)
  • Polar’s API is temporarily down
  • The license key was revoked from the customer portal

Fix:

  1. Check your internet connection — open a browser and visit polar.sh.
  2. If Polar is down, wait a few minutes and retry.
  3. If revoked, go to the customer portal to check key status.

”Machine fingerprint mismatch”

Section titled “”Machine fingerprint mismatch””

Triggered when hardware changes significantly (e.g. new CPU, or after a VM migration).

Fix:

  1. Go to the customer portal → deactivate the current machine.
  2. Re-activate on the same (or new) machine with the license key.

Browser / profile issues

Section titled “Browser / profile issues”

Browser doesn’t launch

Section titled “Browser doesn’t launch”

Check:

  • Is the profile already running? A profile can only have one browser instance.
  • Check Logs (sidebar) for [browser] error lines.
  • If the log shows DevToolsActivePort file doesn't exist, the Chromium process crashed on startup. Try deleting the profile’s Default/ directory from Settings → Profiles → ⋮ → Reset browser data.

Bot detection triggered

Section titled “Bot detection triggered”

If a site detects automation despite stealth mode:

  1. Check that you’re using the zendriver engine (not patchright) for high-security sites.
  2. Ensure the proxy is working — a datacenter IP is often flagged faster than a residential one.
  3. Regenerate the profile fingerprint: Profile → Fingerprint → Regenerate.

LLM / AI agent issues

Section titled “LLM / AI agent issues”

”API key invalid” error in runs

Section titled “”API key invalid” error in runs”

Fix: Go to Settings → LLM Keys and re-enter the key. Keys are stored locally and never sent to Fantommind servers.

Agent loops or exceeds max steps

Section titled “Agent loops or exceeds max steps”

The agent will stop at the Max steps limit set on the task. Increase it if the task is legitimately long, or refine the prompt to be more specific.

App crashes / won’t start

Section titled “App crashes / won’t start”
  1. Check Windows Event Viewer for crash logs under Application.
  2. Check the sidecar log: %APPDATA%\com.fantommind.app\logs\sidecar.log
  3. Restart the app. The sidecar auto-restarts via Tauri’s sidecar watchdog.
  4. If the crash is reproducible, open an issue on GitHub with the log snippet.

Update issues

Section titled “Update issues”

If the auto-updater fails, download the latest installer from GitHub Releases and run it manually. It installs over the existing version without losing data.