My cron job shows as missed

Open the cron job's page and look at Ping History. If the run you expected isn't listed, its check-in never reached Uptime; start with the first three sections. If it is listed as Late, it arrived after its deadline; skip to the timing sections.

If the check-in is rejected

Run the job's curl command by hand and read the status code:

curl without -f exits successfully even when Uptime refuses the request, so a rejected check-in can go unnoticed in your job's logs. The crontab line Uptime suggests uses curl -fsS.

If the job fails before it checks in

The check-in is meant to be the job's last step, so a job that crashes or exits early never sends it. That is the monitor working as intended. Check the job's own logs for the failed run.

If the job never ran

Your scheduler may not have run the job at all: a stopped server, an expired container, a crontab that was overwritten. Confirm the scheduler's last run time on the machine itself.

If the schedule or time zone doesn't match

Uptime expects a run at the times Cron Expression produces in the job's Timezone, which is UTC unless you changed it. A job scheduled for 0 2 * * * on a server set to New York time runs five or four hours later than a monitor left on UTC expects.

Open the cron job with Edit and make Cron Expression and Timezone match the scheduler exactly.

If the job takes longer than the grace period

The deadline for each run is its scheduled time plus the Grace Period, 300 seconds by default. The check-in comes at the end of the job, so a 20-minute job is late every time on a 5-minute grace period. A run is marked missed once the next run's deadline has also passed.

Set Grace Period to longer than your slowest run with Edit. It goes up to 86,400 seconds (24 hours).