Azure Functions Timer Trigger Cron (NCRONTAB)
Azure Functions timer triggers use NCRONTAB, a six-field expression that starts with seconds: {second} {minute} {hour} {day} {month} {day-of-week}. This is one field more than standard Linux cron, so a five-field expression will not work.
The 6-field NCRONTAB format
Azure's order is {second} {minute} {hour} {day} {month} {day-of-week}. To run every 5 minutes: 0 */5 * * * * (second 0, every 5th minute). The leading 0 is the seconds field that Linux cron does not have.
Where it goes
Set it in the function's function.json as the schedule binding, or in the [TimerTrigger("0 */5 * * * *")] attribute in C#.
Common examples
Top of every hour: 0 0 * * * *. Every day at 09:30: 0 30 9 * * *. Every weekday at 08:00: 0 0 8 * * 1-5.
Gotcha vs Linux cron
If you paste a standard 5-field crontab line, Azure reads your minutes as seconds and shifts everything. Always add the seconds field.
FAQ
How many fields does an Azure Functions cron expression have?
Six. NCRONTAB is {second} {minute} {hour} {day} {month} {day-of-week} — one more than Linux cron's five fields.
What is the Azure cron for every 5 minutes?
0 */5 * * * * — second 0, every 5th minute. Note the leading seconds field.
Why does my Linux crontab line misfire in Azure Functions?
Azure expects 6 fields with seconds first. A 5-field line is read as {second minute hour day month dow}, shifting every value. Add a leading seconds field.