Customizer Broke, says You are customizing Beta Wordpress

[xllentech]

I updated to Wordpress WordPress 4.9-RC2-42139 from 4.8.3

When I updated, update process worked fine. but after the update, I went to Appearance-> Customize ..and it just says "You are customizing" in small letters and below it says "Beta Wordpress". and the rest of the whole screen is blank as in screenshot.

BTW, I am using InstantWP for beta purpose, not sure if that makes any difference. I have had no other issues till date for over a year.

Let me know if you need more information.

[xllentech]

Customizer Screenshot

[westonruter]

@xllentech Hi, what plugins and theme do you have active?

Is there an error appearing in your PHP error log? It seems like you may be having a PHP fatal error.

[westonruter]

Please also look at your browser's JavaScript console to see if there are errors there.

[xllentech]

I am using Total theme, paid theme from themeforest.

I had deactivated all plugins, still the same issue. I have 9 plugins active..

Contact Form 7

Slider Revolution

Templatera

WordPress Beta Tester

WPBakery Page Builder

XllenTech Calendar Pro ADD-ON (Self-developed)

XllenTech English Islamic Calendar (Self-developed)

Xllentech Salat Timings (Self-developed)

XllenTech Upcoming Events (Self-developed)

Javascript error tha comes up in Devtools in Chrome is as below:

Uncaught TypeError: Cannot set property 'parent' of undefined

at Function.add (customize-base.min.js:1)
at Object.<anonymous> (customize-controls.min.js:3)
at Function.each (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,underscore,shortcode,utils,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jqu&load[]=ery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=4.9-RC2-42139:2)
at HTMLDocument.<anonymous> (customize-controls.min.js:3)
at i (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,underscore,shortcode,utils,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jqu&load[]=ery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=4.9-RC2-42139:2)
at Object.fireWith [as resolveWith] (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,underscore,shortcode,utils,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jqu&load[]=ery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=4.9-RC2-42139:2)
at Function.ready (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,underscore,shortcode,utils,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jqu&load[]=ery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=4.9-RC2-42139:2)
at HTMLDocument.K (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,underscore,shortcode,utils,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jqu&load[]=ery-ui-core,jquery-ui-widget,jquery-ui-mouse,jquery-ui-sortable&ver=4.9-RC2-42139:2)

[westonruter]

@xllentech could you please add the following to your wp-config.php:

define( 'SCRIPT_DEBUG', true );
define( 'WP_DEBUG', true );

This will allow you to more easily see what the error is.

Additionally/alternatively, if you could send a ZIP of all your active themes and plugins to trac-wp-core-42499@xwp.co I will then be able to test locally on my environment.

[westonruter]

I tried to reproduce the problem with the themes and plugins but I was unable. As we discussed over email, please share if you encounter the cause and there is a core defect to fix.