Starting with WordPress 5.5 GP Premium plugins elements and page-header started throwing javascript errors due to missing declaration of wpColorPickerL10n. The full error is below:
Uncaught ReferenceError: wpColorPickerL10n is not defined
at h.<computed>.<computed>._create (color-picker.min.js?ver=5.5:2)
at h.<computed>.<computed>.h.isFunction.a.<computed> [as _create] (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:45)
at h.<computed>.<computed>._createWidget (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:45)
at new h.<computed>.<computed> (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:45)
at HTMLInputElement.<anonymous> (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:45)
at Function.each (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:8)
at n.fn.init.each (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:8)
at n.fn.init.h.fn.<computed> [as wpColorPicker] (load-scripts.php?c=0&load[chunk_0]=underscore,shortcode,utils,jquery,backbone,wp-util,wp-backbone,media-models,moxiejs,plupload,wp-plupload,jquery-ui-core,jquery-u&load[chunk_1]=i-widget,jquery-ui-mouse,jquery-ui-sortable&ver=5.5:45)
at i.ready (load-scripts.php?c=0&load[chunk_0]=mce-view,imgareaselect,image-edit,wp-hooks,heartbeat,customize-base,customize-controls,customize-widgets,accordion,wp-sanitize,c&load[chunk_1]=ustomize-nav-menus,jquery-ui-slider,jquery-touch-punch,iris&ver=5.5:13)
at Object.<anonymous> (load-scripts.php?c=0&load[chunk_0]=mce-view,imgareaselect,image-edit,wp-hooks,heartbeat,customize-base,customize-controls,customize-widgets,accordion,wp-sanitize,c&load[chunk_1]=ustomize-nav-menus,jquery-ui-slider,jquery-touch-punch,iris&ver=5.5:13)
As far as I checked, the faulty JS file is wp-color-picker-alpha.js and its minified counter-part, wp-color-picker-alpha.min.js. Can you please update this in order for it to be fully compatible to 5.5? Right now the graphic customizer in the admin section is unusable due to this.
Topic: WordPress 5.5 javascript error on wpColorPickerL10n