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My website won't back up or sync because of loopbacks

Have you noticed that one of your sites isn't generating backups, or that its installed plugins don't even show up in Modular DS? When a site stops syncing like this, the most likely cause is a loopback problem.

We'll explain what they are, why they affect your site's connection with Modular DS, and how to fix it.

What loopbacks are and why they matter

A loopback is a request that WordPress makes to itself to run background tasks.

WordPress uses them to check the site's status, launch scheduled tasks (the WP-Cron system) and verify plugin and theme compatibility.

They're part of how any WordPress site works normally. Without them, features like scheduled post publishing or automatic maintenance processes stop running reliably.

Modular DS relies on those same requests to sync your site's information and to run backups.

That's why, when loopbacks fail, the site can't sync and backups don't even start.

On top of that, the problem isn't only about Modular DS: it's something your site needs to work properly.

How to tell if it's a loopback problem

There are several signs that confirm it:

In the site's updater, the plugins don't sync properly: none may show up at all, or the list may not match your WordPress and, when you reload, the updater keeps loading without finishing.
In "Site settings", under "WordPress 1-click login user", the "User name" dropdown appears empty, because the site never managed to sync.
From WordPress itself, under "Tools" and then "Site Health", you'll see a notice that the site could not complete a loopback request.

You can also confirm it in the site's settings, where the login user appears unselected:

How to fix it

Loopbacks are blocked at the server level, so the fix isn't inside Modular DS. But before contacting anyone, there's a quick check you can do yourself.

Rule out a security plugin first

Some security plugins (like Wordfence or Security Ninja) include a firewall that can block these internal requests. Deactivate it on the affected site only and check again whether it's resolved.

Keep in mind that the site's information refreshes every 24 hours, so checking right away may still show the previous state.

To verify it right now, reload the Modular DS updater or run a manual backup and check whether it works.

If backups start working again, that plugin was the cause and you can adjust its settings.

If the same plugin works fine on your other sites, it's unlikely to be the cause, but it's still worth ruling out in a minute.

Contact your hosting provider

If the plugin wasn't the problem, the block is on the server and your hosting provider needs to look into it.

Tell them that WordPress loopback requests to the site's own domain aren't working, and ask them to check whether something is blocking them: a server security rule, the firewall, or the server not being able to connect to itself.

With that hint, your hosting provider will know where to look.

For whoever manages the server (your hosting provider, or you if you manage your own server): the fastest way to pinpoint it is to search the access logs for the requests to /wp-cron.php, /wp-admin/admin-ajax.php and Modular DS's own loopback request /wp-load.php?origin=mo&type=lb. If they show up with errors, the block is in how the server processes them (ModSecurity rules, PHP configuration or SSL). If they don't show up at all, something is cutting them off before they arrive: the firewall, the server's own IP being blocked, or the server not being able to resolve its own domain.

Do you need help with anything else? Email us at help@modulards.com or contact us via the support chat, and we'll be happy to help you.

Updated on: 18/09/2026

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