In my current WordPress project I get the following error message when I view my cronjobs:
There was a problem spawning a call to the WP-Cron system on your site. This means WP-Cron events on your site may not work. The problem was:
Unexpected HTTP response code: 503
It causes several of my plugins to not work correctly, because the cronjobs don't trigger. How can I fix this? What do I have to do to the server configuration for this to work? Why does this error occur anyway? I don't quite understand it.
When I set up the same system locally with XAMPP, everything works fine, so it has to do something with the server.
I know there is a workaround in setting up a real cronjob on the server, but that is not an option.