How to Debug a Silent Agent Failure at 3am

You wake up, check your phone, and something's wrong. Your AI assistant was supposed to send a report at midnight. It didn't. Or maybe it ran, but nothing happened. No error. No message. Just silence.

This is the worst kind of failure. A crash with an error message is easy — you fix the error. But when your agent just… stops? That's a puzzle. And at 3am, you don't have patience for puzzles.

Here's a step-by-step triage guide. Work through it in order. Most silent failures fall into one of five buckets, and this guide will get you to the cause in under 15 minutes.

Step 1: Confirm It Actually Ran

Before you assume something broke, confirm the agent actually triggered at all.

Check your scheduler logs. If you're using a cron job, run this:

grep CRON /var/log/syslog | tail -50

Or on a Mac:

log show --predicate 'subsystem == "com.apple.xpc.launchd"' --last 2h | grep -i cron

If you're using a task scheduler or automation platform, check its run history — most have a dashboard that shows "last ran at" timestamps.

Step 2: Find the Last Log Entry

Your agent should be writing logs somewhere. Find the most recent entry and read it carefully.

If logs go to a file:

tail -100 /path/to/your/agent.log

If logs go to a service like systemd:

journalctl -u your-agent-name --since "3 hours ago"

Step 3: Check for Silent Crashes

Sometimes a process starts, hits a problem, and exits without writing anything useful. This is common when:

• A required tool or library isn't installed
• A file the agent needs doesn't exist
• Memory ran out mid-run

Check exit codes if you have them. In a shell script:

echo "Exit code: $?"

For processes managed by systemd:

systemctl status your-agent-name

Look for lines like Main PID: 1234 (dead) or code=exited, status=1.