“Help! The WordPress 5.5 upgrade broke my site!”

The WordPress 5.5 upgrade was released earlier this month with a bevy of new features. We updated here on the Agathon blog without any issue and are especially enjoying the new block features for blog post creation and editing.

That said, there are some plugins that may be incompatible with this particular upgrade. That’s causing errors for some bloggers and leading others to avoid upgrading. We’ll explain more about what causes that incompatibility and how you can address it down below.

Remember, keeping WordPress core updated ensures the health and security of your site. It’s important to deal with compatibility problems rather than leave your site on an older version!

The backstory: understanding jQuery and the WordPress 5.5 upgrade

If you want to understand the ‘why,’ start here; if you just want to know how you can fix it, jump to the next section! 🙂

jQuery is a JavaScript library that a ton of plugins rely on, as does WP Core. In order to prevent every. single. plugin. from bundling its own copy of jQuery within its code, WordPress core provides a single copy of the jQuery library. Plugin authors that follow best practices can use this copy of jQuery.

Like other code libraries, jQuery is updated from time to time to add new features, remove old and inefficient functionality, and fix bugs. As WordPress updates the version of jQuery it uses, those updates can alter or remove functionality that plugins rely on. Plugin authors may need to modify their use of jQuery to work properly with each new version.

Realistically, plugin updates don’t always happen immediately. So WordPress core has historically included a tool called jQuery Migrate alongside with the jQuery library itself; the migrate tool provides backwards compatibility with older versions of jQuery, allowing plugin authors time to update their code to no longer rely on older features.

Helpful as it may be, the inclusion of jQuery Migrate tool has prevented WordPress core from updating to the most recent version of jQuery. So, as part of a multi-step plan to provide the latest jQuery in WordPress core, the WordPress team removed jQuery Migrate from core as of version 5.5. Without the benefit of jQuery Migrate to “paper over” their reliance on outdated code, some older plugins are no longer functional. In some cases this prevents aspects of sites or the dashboard from working properly.

Okay, that’s the why. Let’s look at how to fix it!

Use the jQuery Migrate Helper plugin to restore functionality to older plugins/themes

If the WordPress 5.5 upgrade has exposed errors in older plugins on your site, there’s a fairly simple solution. The Enable jQuery Migrate Helper plugin adds the jQuery Migrate bridge back to your site. It also providing information about the warnings and incompatibilities. Once you have those warnings, you can reach out to plugin authors and/or begin to investigate alternative up-to-date plugins.

What you need to do to prepare for WordPress 5.6

Unfortunately, the Enable jQuery Migrate Helper plugin won’t work once WordPress 5.6 is released. At that time, WordPress will release another tool to replace the current one. But using those plugins is just a patch and doesn’t address the bigger issue.

Rather than avoiding the WordPress 5.5 upgrade because of plugin errors (since those are not likely to go away), we recommend using this time to address any errors. You can replace any incompatible plugins and themes so you’re ready for the next update. Once you’ve addressed those errors, you should be able to disable the Enable jQuery Migrate Helper plugin. Once you’re sure everything is working properly, you can delete it altogether.

How to roll back to 5.4 if the WordPress 5.5 upgrade reveals errors

If your site is still showing errors after you’ve installed the Enable jQuery Migrate Helper and you need to roll back to WordPress 5.4, you can do so using the WP Downgrade plugin. This should be a temporary solution while you investigate the errors.

And, of course, if you’re hosted with us, are seeing issues with WordPress 5.5, and the Enable jQuery Migrate Helper plugin doesn’t seem to be doing the trick, drop us a line before downgrading; we may be able to help!


In summary, you should keep your site updated for both performance and security. Older plugins may be incompatible the WordPress 5.5 core update because of the way they use jQuery. Using the Enable jQuery Migrate Helper plugin can help bridge those incompatibilities by providing missing functionality while showing errors and warnings on your dashboard so you can address them.

You may need to repeat this process when you upgrade to WordPress 5.6. But choosing regularly maintained and update plugins can help reduce these types of incompatibilities.

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