Automatically retry a cron job when the server hiccups

The most important rule

We only retry what certainly did not run

A newsletter that goes out twice or an import that books everything twice is worse than a missed run. That is why Cronjob.de distinguishes precisely: if the call never reached your script, a second attempt is safe. If the script may already have done its work, we do not retry but alert you as usual.

Tip

Your script can ask for a later attempt itself

Sometimes your script knows best that now is not a good time – for example because the previous run is still working or a service it needs is not answering. If retries are switched on and your script then answers with status 503 before changing anything, we try again later. Important: the 503 has to come before the actual work begins.

<?php
$lock = fopen(__DIR__ . '/export.lock', 'c');
if (!flock($lock, LOCK_EX | LOCK_NB)) {
    http_response_code(503);   // previous run still working: try later
    exit;
}
// ... the actual work ...
echo 'OK';

FAQ

Common questions

Can the retry make my script run twice?

No. We only retry when the call certainly did not reach your script: the server was unreachable, refused the connection or answered with 502, 503 or a Cloudflare error such as 522. After a 500, a timeout or a redirect your script may already have run – then we never retry.

When exactly do the retries happen?

After 1, 5 and 15 minutes – one, two or three attempts depending on your setting. Since a pass on our servers takes up to a minute, an attempt can come one minute later. If your cronjob is due again anyway before that, the retry is skipped.

Do I get a failure alert if the retry works?

No. We only alert you once all attempts have failed. The log still shows both: the failed run and the successful attempt, marked as “Retry 1”.

Does the retry come from the same server?

No, deliberately from another one of our servers. If the hiccup is in the connection between our server and yours, it often works from there. If you allowed our addresses in a firewall, please use the complete list at cronjob.de/ips.txt so the retries get through too.

Is a cronjob that runs every minute retried too?

No, that would be pointless: the next scheduled run comes a minute later anyway. Retrying helps most with tasks that run rarely – hourly, at night or once a day.

Which plan includes retries?

From Plus (€1.49 per month, €17.88 per year), at no extra cost, also on Unlimited and during the first 14 days after signing up. You switch it on per cronjob in the “Success check” tab.