Jenkins version is 2.235.5 (I should update it to next LTS version 2.249).

I configured Jenkins to run a job periodically every 30 days: Build Triggers → Build periodically → Schedule:

H 3 */30 * *

And now I see:

Would last have run at Saturday, October 31, 2020 3:20:39 AM EDT; would next run at Sunday, November 1, 2020 3:20:39 AM EST.

So it will be started again after 1 day, not 30 days…

How to run a job periodically every 30 days?