It is common that after update WordPress to 5.5 version you got error.

ReferenceError: commonL10n is not defined error

Because of this javascript conflict, all elements with jQuery and Ajax will stop working.

For the quick fix of this Javascript / Ajax conflict just copy and paste following php WordPress action in you function.php.



// Fix ReferenceError: commonL10n is not defined error
/// fix error update wordpress 5.5
add_action( 'admin_footer', function () {
	? >

	< script >
		if ( typeof commonL10n === 'undefined' ) {
			var commonL10n = { dismiss : 'Dismiss' };
		}
	

	< ? php
}, 100 );

commonL10n error Error WordPress
WordPress