Last Updated on September 1, 2021
There have been many reports of sites breaking when WordPress has been updated to version 5.5. This is due to the developers removing a library called jquery-migrate. They did this so that WordPress only used the latest versions of some libraries, but as a result, some plugins and themes stopped working correctly.
WordPress explains the problem as follows:-
“With the update to WordPress 5.5, a migration tool known as jquery-migrate will no longer be enabled by default. This may lead to unexpected behaviors in some themes or plugins who run older code.”
The plugins or themes don’t have to be old to cause this problem. Many plugins are still actively developed but used the jquery-migrate library and this change broke those plugins. Indeed, a post on WordPress suggests that as many as 2,400 plugins are liable to break as a result of this change. As plugin developers upgrade their plugins, this list will get smaller but still, you should not be surprised if you run into a problem.
The easiest way to address this problem is to install the “Enable jquery migrate helper” plugin. You’ll find it listed in the plugin directory and can be installed in the usual way.
As you can see, there have been over 100,000 installations of this plugin so that gives you some idea of the scale of this issue.
The plugin will show you a message on the dashboard and if there is a problem then it will show a warning.
Once installed you can upgrade WordPress to 5.5 and you shouldn’t be caught by this problem.
Note, by installing this plugin you’re not actually fixing the issue that was breaking your site. The plugin will enable your site to work again but the issue that caused it to break in the first place – most likely old plugin code – will still be there. The warnings will continue to show until the plugins and themes have been updated to versions that are fixed. Once the warnings stop displaying, you can remove the jquery-migrate helper plugin.
If, after a little while, there is still no update for the theme or plugin that you’re using then it’s likely that theme or plugin is no longer being actively developed. If that’s the case then you should look at replacing it with another plugin that gives you the same functionality but is still being actively developed. That’s because having old, deprecated plugins sitting on your site that aren’t being properly developed is a security risk.