Hello there,
Most likely there is a plugin or theme that is using the is_ajax
function. This should continue to work. This is a PHP notice that this function has been deprecated and should be updated.
You could use the String Locator plugin to search the site for is_ajax
. It will still be in WooCommerce a few times so you’ll want to find where it’s used outside of that.
If you find any, let the developer of the plugin/theme know about it so they can update their code.
Take care,