Version 5.5 of WordPress has included changes to jQuery to bring it up to modern development standards. For many years, WordPress has been shipping with jquery-migrate to ensure sites didn’t break where plugins and themes have been using a significantly outdated jQuery 1 syntax. As jquery-migrate provides a fix to bridge issues with old code, the intent was to use it as a transition tool.
However, many plugins and themes had failed to update old jQuery syntax (now 14 years old) and had simply relied on the fact that WordPress (via jquery-migrate) would partially correct the bad syntax.
As WordPress intends on moving to jQuery 3 (since all old versions are unsupported), this means breaking the compatibility with jQuery 1.x so that an updated version of the plugin can be utilised to bridge the gap now to jQuery 3.
Issues your site may experience (but not limited to) are:
- Broken sliders
- Broken menus
- Look and feel issues
- Issues with AJAX content loading
This should not be seen as an issue for WordPress 5.5, but generally an issue where paid themes and/or plugins haven’t got a valid license to keep them up-to-date.
All high quality themes and plugins should have already released updates to ensure jQuery compatibility, if your site is reliant on a theme or plugin where this isn’t the case then we recommend finding an alternative. Lack of active development represents potential security issues and this is one of the most commonly exploited areas of WordPress based sites.
WordPress do make the older jquery-migrate available via a plugin for those who need a temporary fix while they investigate the underlying issues. This plugin is: https://wordpress.org/plugins/enable-jquery-migrate-helper/
- Within the WordPress plugins area and search for “Enable jQuery Migrate Helper“:
- Install and activate the plugin.
- While remaining logged in, browse the site record all errors reported:
- For each plugin and theme, determine if it’s up-to-date and if no updates are listed if a license is required (eg, it’s a paid plugin).
- After all updates have been applied, review again. If there are no further issues, the plugin should be uninstalled.