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Troubleshooting

CoT events not appearing in TAK

Work through these steps in order:

1. Verify CoT is being generated

Set COT_URL=log://stdout and run your tool. If CoT XML prints to the console, PyTAK is working and the problem is network connectivity or configuration.

COT_URL=log://stdout python3 send.py

2. Connect directly to an EUD

Bypass the TAK Server and connect directly to an ATAK/iTAK/WinTAK device on the same network:

COT_URL = tcp://192.168.1.50:4242

Replace 192.168.1.50 with the device's IP. In ATAK, enable the streaming server under Settings → Network → Streaming.

3. Check multicast support

If using udp:// (Mesh SA), confirm your network switch and router support multicast. Many managed switches disable multicast by default. Try switching to tcp:// or udp+wo:// to rule out multicast issues.

4. Enable debug logging

DEBUG=1 python3 send.py

Look for connection errors, dropped packets, or queue warnings in the output.

Enter PEM pass phrase: prompt

This prompt appears when your private key is password-protected (the default when using TAK Server's makeCert.sh).

Option 1 — Set the password in config (recommended):

PYTAK_TLS_CLIENT_PASSWORD = atakatak

Option 2 — Remove the passphrase from the key:

openssl rsa -in pytak.key -out pytak.nopass.key

Then point PYTAK_TLS_CLIENT_KEY at the new file.

Option 3 — Accept the prompt and enter the password each time PyTAK starts.

certificate verify failed error

ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed:
self signed certificate in certificate chain

The TAK Server is using a self-signed certificate or a certificate signed by a private CA that your system doesn't trust. This is expected for most TAK Server deployments.

Option 1 — Provide the CA chain (recommended):

Export your TAK Server's CA certificate (ca.pem) and set:

PYTAK_TLS_CLIENT_CAFILE = /etc/pytak/ca.pem

The CA cert is typically found at /opt/tak/certs/files/ca.pem on the TAK Server.

Option 2 — Disable verification (development only):

PYTAK_TLS_DONT_VERIFY = 1

Warning

Disabling verification removes protection against man-in-the-middle attacks. Only use in isolated test environments.

hostname mismatch / CN verification error

ssl.SSLCertVerificationError: hostname ... doesn't match

The certificate's Common Name (CN) doesn't match the hostname in COT_URL.

Option 1 — Set the expected hostname:

PYTAK_TLS_SERVER_EXPECTED_HOSTNAME = takserver.example.com

Option 2 — Disable hostname checking (development only):

PYTAK_TLS_DONT_CHECK_HOSTNAME = 1

aiohttp not installed

ImportError: Marti HTTP transport requires aiohttp. Install with: pip install pytak[with_aiohttp]

The marti:// URL scheme and tak:// certificate enrollment require the aiohttp extra:

pip install pytak[with_aiohttp]

Or on Debian/Ubuntu:

sudo apt install -y python3-aiohttp

takproto not installed

TAK_PROTO is set to '1', but the 'takproto' Python module is not installed.

Install the takproto extra:

pip install pytak[with_takproto]

Queue full warnings

Queue full, dropping oldest data. Consider raising MAX_IN_QUEUE or MAX_OUT_QUEUE

Your sender is producing events faster than the network (or your receiver) can consume them. Increase the queue size:

MAX_OUT_QUEUE = 500
MAX_IN_QUEUE = 1000

Or reduce your send rate by increasing PYTAK_SLEEP.

FreeTAKServer: events dropped or connection refused

FTS has built-in anti-DoS rate limiting that rejects clients sending too fast. Enable compatibility mode:

FTS_COMPAT = 1

Or set a fixed sleep interval:

PYTAK_SLEEP = 3

Windows-specific issues

UDP multicast doesn't work

Windows restricts how multicast sockets bind. Try:

  • Use udp+wo:// (write-only) instead of udp://
  • Connect directly via tcp:// or tls://

Setting environment variables in PowerShell:

$env:COT_URL = "tcp://takserver.example.com:8087"
$env:DEBUG = "1"
$env:PYTAK_TLS_CLIENT_PASSWORD = "atakatak"

Check a variable:

$env:COT_URL

Still stuck?

  1. Run with DEBUG=1 and capture the full output
  2. Check open issues to see if it's a known problem
  3. Open a new issue and include: your OS, Python version, PyTAK version, COT_URL (redact passwords), and the debug output