WordPress Customizer Does Not Work

[tetonbabe]

This is probably due to bad data somewhere in my database. I see the problem with WordPress 4.5.2 and with all plugins disabled. Although I cannot tell you how to duplicate the problem, the fix is a safe fix. The problem is due to php files referencing data.attachment.sizes when that is undefined. In wp-includes/, there are 3 WordPress php files that contain the text 'data.attachment.sizes'. #1 already has the fix, which is to check whether 'undefined' !== typeof data.attachment.sizes. I added that test to the 2nd file, which fixed my problem. I suggest it be added to the 3rd file as well, for safety. The 3 files are:

1 - wp-includes/media-template.php.
2 - wp-includes/customize/class-wp-customize-site-icon-control.php, line 62
3 - wp-includes/class-wp-customize-media-control.php, line 156

[swissspidy]

Hey there,

Thanks for your report! We're already tracking the exact same issue in #36749, which is slated for the 4.5.3 release, due out soon.