What’s the issue?
To be clear this is NOT an issue with WordPress.
Plug-in and Theme Developers who do not keep their software up-to-date and that do not use best practices are the root issue. For this reason, we recommend turning off auto-updates and using a staging environment to test major updates. Unfortunately, some hosts do not provide either of these options. We will be release a quick guide soon on this subject. In the meantime, if you need help with this issue, please let us know.
How do figure out if there is a problem?
For jQuery Migrate, this will likely present itself in your menus, carousels/sliders and other interactive features.
If you or your web hosting company use auto-updates on your website, we recommend testing your menus & other interactive features, as your users may already be affected.
What can I do myself to fix it?
To be up front, you may not be able to “fix it” but you can patch and restore functionality of your website
WordPress has released a plug-in patch to allow you time to update your themes and plugins. You can download Enable jQuery Migrate Helper from the WordPress website.
Or from your Plug-ins page in your WordPress Admin, you can click you “Add New” and search “Enable jQuery Migrate Helper”. Click Install and Click Activate.
This doesn’t fix the issue, but it does reactivate jQuery Migrate which will allow you time to update your Themes and Plugins.
It’s patched! What do I do now?
For this reason, we recommend turning off auto-updates and using a staging environment to test major updates. Unfortunately, some hosts do not provide either of these options.