Short-cut: If you are developing a new website and see this warning, then simply keep the UpdraftPlus settings page open whilst you back up. You don’t need to read any of the rest!
UpdraftPlus is a WordPress plugin; as such, it relies on WordPress running and handing it the opportunity to do something; in particular, it relies upon WordPress’s scheduled task engine running properly.
Thus if WordPress’s scheduled task engine (“WP Cron”) does not run, then neither can UpdraftPlus. So, if your website has zero visitors between midnight and 5am, and if your backup is scheduled to run just after midnight, then it won’t actually get to run until a visitor turns up at 5 am.
There is usually no danger of this becoming a problem, because even very unpopular websites tend to get visited by several search engines as long as those search engines are aware of them.
However, if enough of the following factors are present, then your backup may not be able to complete:
- Your website is not known by search engines
- Your website has almost no other visitors (e.g. is under development, and only the developer visits it, during office hours)
- Your webserver only allows code to run for a short time
- Your website is larger, and is being uploaded to a cloud backup service
- You schedule backups to run very frequently (e.g. every 4 hours) so that multiple backup jobs may be competing for resources
Another way that this can happen is if your WordPress scheduler has been disabled (you’d usually know if this is so and understand the rest of this paragraph), and you’re instead running the scheduler via an automated task you’ve set up to call wp-cron.php directly. If you only call wp-cron.php once an hour, then this is like just having one visitor per hour as far as WordPress’s scheduler is concerned.
Note: If you were sent to this page by a warning from your copy of UpdraftPlus, then this does not mean for sure that your backups are definitely failing because of this problem – it just means that UpdraftPlus has detected a lack of visitors. It may be that there are still enough. The warning is advisory of a potential problem.
This issue is not a novelty of UpdraftPlus; it is the case for every WordPress backup plugin with scheduled backups.
What are the solutions? Any of these should help:
- If you’re a developer, or your site was only just launched, then don’t set your backup time to 1 a.m. until after you launch the site and have some visitors and your site is known by search engines.
- Your web hosting company’s control panel may have the facility to set up automated tasks – you could set up a task to visit the site every 1 minute. This has a negligible impact upon on performance. If you want to look at this option, you should ask your web hosting company for help – we can’t provide specific guidance.
- Sign up with a facility like http://uptimerobot.com/, https://www.pingdom.com/free/ or http://www.easycron.com/tutorials/how-to-set-up-cron-job-for-updraftplus to get some more automated visits to your website.
- If you’re just developing the site and need a backup *now*, then just keep the UpdraftPlus settings page open – it will make silent calls to the WP scheduling code in the background every few minutes (UpdraftPlus 1.7.15 and later).
- Load up the site’s front page and hit “reload” every 5 minutes until the backup has completed.
- If you disabled WordPress’s default “cron” engine, and attempted to call it another way, then seeing this message means that you are not calling it regularly enough. Call it each minute. This has a negligible impact upon performance; if your web hosting company says otherwise, then this is bad advice (your author is someone who has both run a web hosting company and analysed and contributed to cron code in WordPress core).
Note: When using automated visits, certain caching plugins (such as WP Super Cache) can prevent the scheduler from being triggered. If you are having issues, ensure that the automated visit is directed to an uncached page or file.