Invalid cron expression in n8n
Why malformed cron expressions cause workflows to run at wrong times or not at all
What is this issue?
Cron expressions define when scheduled workflows run. An invalid or incorrect expression may cause the workflow to never trigger, run at the wrong time, or run far more frequently than intended.
Common cron mistakes:
•Using 6 fields instead of 5 (or vice versa)•Confusing day-of-week numbering (0-6 vs 1-7)•Setting impossible combinations (Feb 30)•Typos in special characters (* vs ?)
Why is this dangerous?
Missed executions
Critical workflows may never run if the cron expression is invalid.
Wrong timing
Workflows run at unexpected times, causing data sync issues or user confusion.
Resource waste
Expression may trigger far more often than intended, consuming resources.
Silent failures
n8n may not clearly report that a cron expression is invalid.
How to fix it
- 1
Use a cron validator
Test expressions at crontab.guru before deploying to n8n.
- 2
Check n8n cron format
n8n uses 5-field cron (minute, hour, day, month, weekday)—not 6-field.
- 3
Test with short intervals
Before deploying, set a 1-minute interval to verify the trigger fires.
- 4
Use the UI editor
n8n's Schedule Trigger has a visual editor that prevents syntax errors.
Scan your workflow now
Upload your n8n workflow JSON and detect invalid or suspicious cron expressions.