Jackett API Key Error stopping Sonarr or Radarr? Learn how to fix 401 Unauthorized, invalid keys, and connection issues with step-by-step proven methods.

Jackett API Key Error: Quick Fixes for Seamless Torrenting

Jackett is a popular tool among torrenting enthusiasts, especially those using automation tools like Sonarr, Radarr, and Lidarr. It acts as a proxy server that translates queries from these apps into tracker-specific formats, making it easy to integrate various public and private torrent indexers. However, one frustrating issue many users encounter is the dreaded “Jackett API key error.”

This error can bring your automation to a halt, preventing apps from fetching torrents or communicating with indexers. The good news? It’s almost always fixable with a few careful checks.

In this guide, we’ll walk you through what Jackett is, why API key errors occur, how to fix them step-by-step, and how to prevent them in the future.

What Is Jackett and Why Use It?

Jackett is an open-source application that acts as a bridge between torrent indexers and media automation tools like:

• Sonarr (TV series)

• Radarr (movies)

• Lidarr (music)

• Mylar (comics)

These applications rely on Jackett to search for torrents across various sources in a unified way. Each indexer in Jackett is exposed via an API, and this integration is secured by a unique API key.

When you set up Sonarr or Radarr to use Jackett, you must provide the correct Jackett API Key Error a string that authenticates your request. If something goes wrong here, you’ll likely see a Jackett API key error.

Common “Jackett API Key Error” Messages

Users typically encounter one of these error messages when dealing with an API issue:

❌ “Invalid API Key”

• Appears when the key entered into Sonarr/Radarr doesn’t match the one currently active in Jackett.

• Often caused by copy-paste mistakes or recent key resets.

❌ “Could not connect to Jackett”

• Implies a network or service-level issue.

• Jackett might not be running, or the IP/port is incorrect.

❌ “401 Unauthorized”

• A more technical variant of “Invalid API Key.”

• Indicates that authentication has failed—usually due to the wrong key or permissions error.

These messages usually show up within the app logs, the UI connection test, or in the browser when trying to connect manually.

Root Causes of the Jackett API Key Error

Before jumping to solutions, it’s important to understand why the error occurs:

1. Incorrect API key copied

   • The most common cause. Users copy the wrong string or include extra characters.

2. Jackett server not running

   • If the service is offline, no key will work.

3. URL/IP mismatch

   • Entering localhost on a remote machine or using the wrong local IP will block access.

4. Port misconfiguration

   • Jackett typically runs on port 9117. Changing it without updating your apps leads to a connection issue.

5. Firewall or VPN interference

   • Firewalls, antivirus tools, or VPNs can block access to the Jackett API.

6. Old versions or permission issues

   • Outdated Jackett or missing admin rights can cause the API to misbehave.

How to Fix the Jackett API Key Error (Step-by-Step)

Here’s how to get your Jackett integration back on track:

✅ Step 1: Locate Your Correct Jackett API Key

1. Open Jackett in your browser:
   http://localhost:9117 (or your remote IP/port)

2. Go to the Dashboard

3. Look for the API Key at the top. It should be a long alphanumeric string.

📌 Pro Tip: Use the “copy” icon next to the key to avoid extra characters or spaces.

✅ Step 2: Update the Key in Sonarr/Radarr

1. Open Sonarr or Radarr

2. Navigate to:
   Settings → Indexers

3. Edit the Jackett indexer entry

4. Paste the API key into the API Key field

5. Click Test to verify

✅ Step 3: Verify Jackett Is Running and Accessible

• Open a browser and go to:
  http://localhost:9117/UI

• If it doesn’t load, check:

  • Is the Jackett service running?

  • Is the correct port being used?

  • Is the base URL (if set) causing an issue?

Command Line Tip (Linux/Unix):

✅ Step 4: Whitelist Jackett in Firewalls and Antivirus

Make sure Jackett is allowed through your system firewall:

Windows Defender Example:

1. Go to Windows Security → Firewall

2. Click “Allow an app”

3. Add Jackett.exe or your service file

If using a VPN, try disabling it temporarily to test if it’s blocking Jackett.

✅ Step 5: Check Reverse Proxy or Base URL Settings

If you’re running Jackett API Key Error behind a reverse proxy like Nginx, make sure:

• The proxy passes the API requests correctly

• Any base URL (e.g., /jackett/) is also set in the indexer URL in Sonarr/Radarr

Example API call in Postman or browser:

Advanced Troubleshooting Tips

If the error still persists, dig deeper with these techniques:

🧾 Use Logs to Trace Errors

• Jackett logs:
  ~/.config/Jackett/Logs

• Sonarr/Radarr logs:
  Access via System → Logs

⚙️ Enable Debug Mode

Set Jackett to debug mode to get more detailed logs:

Edit jackett.settings.json:

🌐 Test API Key via Browser or Postman

Try pasting this in your browser (replace values):

A successful request returns XML.

🔁 Reinstall Jackett as a Last Resort

If all else fails:

1. Back up jackett.db and jackett.settings.json

2. Uninstall Jackett

3. Reinstall the latest version

4. Restore config files and test again

Preventing Future Errors

You can avoid Jackett API key errors by setting things up more robustly:

💾 Backup Your Working Config

Save your current settings once everything works, including:

• API key

• Indexer list

• Port and URL settings

🧠 Use Environment Variables or Docker Secrets

If running via Docker, store your API key as a Docker secret to avoid accidental changes.

🔄 Always Update Apps Together

Update Jackett and Sonarr/Radarr around the same time to avoid version mismatches.

📍 Use Static IPs or DNS Mapping

If your Jackett server changes IPs, consider assigning a static IP or local DNS mapping like jackett.local.

FAQs About Jackett API Key Errors

Q1: What is a Jackett API key?
It’s a unique alphanumeric code used to authenticate access to Jackett’s API from other apps like Sonarr or Radarr.

Q2: Can I reset my Jackett API key?
Yes. Just delete the key in your settings file and restart Jackett to generate a new one. But be sure to update all apps using the old key.

Q3: Why is my Radarr not connecting to Jackett?
Likely due to a wrong API key, unreachable Jackett URL, or port issue. Double-check the connection test in Radarr.

Q4: Is Jackett safe to use?
Yes, if downloaded from the official source and used responsibly. Avoid pirated content and secure your setup with firewalls and VPNs.

Q5: How often should I update Jackett?
Check for updates monthly. Jackett API Key Error frequently adds new indexers and fixes bugs, so staying updated helps avoid errors.

Conclusion

The Jackett API key error can be frustrating but is usually easy to resolve by checking the basics: API key accuracy, server status, port, and network configuration. With the steps in this guide, you should be back to seamless torrent automation in no time.

Double-check your config files, keep your tools updated, and don’t forget to back up your working setup.

If these steps helped or if you’re still stuck, don’t hesitate to visit the Jackett GitHub page or join the community forums for more support.

Let us know—did one of these fixes work for you? Drop your feedback below!