Is there any way to debug these specifically? I am having a similar issue on my live site, cant reproduce it on my local site. Presumably an offending plugin should be something that uses tiny-mce i.e. has a WYSIWYG editor on the edit page?
My error code:
tinymce.min.js?ver=4607-20180123:14 Uncaught TypeError: Cannot read property 'onpageload' of undefined
at e (tinymce.min.js?ver=4607-20180123:14)
at k (tinymce.min.js?ver=4607-20180123:14)
at h.l.bind (tinymce.min.js?ver=4607-20180123:1)
at o.bind (tinymce.min.js?ver=4607-20180123:3)
at Object.init (tinymce.min.js?ver=4607-20180123:14)
at e (load-scripts.php?c=0&load[]=hoverIntent,common,admin-bar,thickbox,jquery-ui-tabs,wp-mediaelement,heartbeat,autosave,suggest,wp-ajax-response,jquery-color,wp&load[]=-lists,postbox,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,tags-suggest,tags-box,underscore,word-count,post,editor-expand,shor&load[]=tcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,wp-api-request,media-views,media-editor,media-audiovideo,mce-view,im&load[]=gareaselect,image-edit,svg-painter,wp-auth-check,media-upload,jquery-ui-button,editor,quicktags,wplink,wp-embed&ver=4.9.4:670)
at HTMLDocument.<anonymous> (load-scripts.php?c=0&load[]=hoverIntent,common,admin-bar,thickbox,jquery-ui-tabs,wp-mediaelement,heartbeat,autosave,suggest,wp-ajax-response,jquery-color,wp&load[]=-lists,postbox,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,tags-suggest,tags-box,underscore,word-count,post,editor-expand,shor&load[]=tcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,wp-api-request,media-views,media-editor,media-audiovideo,mce-view,im&load[]=gareaselect,image-edit,svg-painter,wp-auth-check,media-upload,jquery-ui-button,editor,quicktags,wplink,wp-embed&ver=4.9.4:670)
at a (tinymce.min.js?ver=4607-20180123:1)
at HTMLDocument.p (tinymce.min.js?ver=4607-20180123:1)
e @ tinymce.min.js?ver=4607-20180123:14
k @ tinymce.min.js?ver=4607-20180123:14
l.bind @ tinymce.min.js?ver=4607-20180123:1
bind @ tinymce.min.js?ver=4607-20180123:3
init @ tinymce.min.js?ver=4607-20180123:14
e @ load-scripts.php?c=0&load[]=hoverIntent,common,admin-bar,thickbox,jquery-ui-tabs,wp-mediaelement,heartbeat,autosave,suggest,wp-ajax-response,jquery-color,wp&load[]=-lists,postbox,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,tags-suggest,tags-box,underscore,word-count,post,editor-expand,shor&load[]=tcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,wp-api-request,media-views,media-editor,media-audiovideo,mce-view,im&load[]=gareaselect,image-edit,svg-painter,wp-auth-check,media-upload,jquery-ui-button,editor,quicktags,wplink,wp-embed&ver=4.9.4:670
(anonymous) @ load-scripts.php?c=0&load[]=hoverIntent,common,admin-bar,thickbox,jquery-ui-tabs,wp-mediaelement,heartbeat,autosave,suggest,wp-ajax-response,jquery-color,wp&load[]=-lists,postbox,jquery-ui-menu,wp-a11y,jquery-ui-autocomplete,tags-suggest,tags-box,underscore,word-count,post,editor-expand,shor&load[]=tcode,backbone,wp-util,wp-backbone,media-models,wp-plupload,wp-api-request,media-views,media-editor,media-audiovideo,mce-view,im&load[]=gareaselect,image-edit,svg-painter,wp-auth-check,media-upload,jquery-ui-button,editor,quicktags,wplink,wp-embed&ver=4.9.4:670
a @ tinymce.min.js?ver=4607-20180123:1
p @ tinymce.min.js?ver=4607-20180123:1
