Error message when saving changes in Customizer

[ruskintech]

I’m frequently getting this error message when trying to publish changes made in the customizer (Dashboard/Appearance/Customize):

Looks like something’s gone wrong. Wait a couple seconds, and then try again.

When I make changes to the same setting in Theme Options (Dashboard/Appearance/Theme Options), and click “save” I don’t seem to get the errors. (What is the practical distinction between these two things, anyway, beside minor differences in the menu options?).

The changes appear to be saved anyway, even when I close the customizer and ignore the “The changes you made will be lost if you navigate away from this page.” warning.

WP 4.9; X 5.2.5; Cornerstone 2.1.7; PHP 7.0.25. I tried disabling all plugins (even cornerstone).

I’ll provide a private link and login momentarily.

Edward

Edit: Also tried adding to wp-config.php:
define( ‘WP_MEMORY_LIMIT’, ‘256M’ );
define( ‘WP_MAX_MEMORY_LIMIT’, ‘512M’ );

[christopher]

Hi there,

Thank you for your detailed information. The preferred way to set the options is the X > Launch > Options. The Appearance > Customize section will not be maintained in the future and will be phased out gradually.

That is why we strongly suggest that you merely use the Options panel. The case might be true regarding the problem as the WordPress 4.9 did some changes regarding the Customize panel which we will look into for sure.

But as mentioned above it is time to get used to the X > Launch > options settings for the theme customization options.

Thank you for your understanding.