This tutorial shows you how to solve CKEditorFuncNum undefined.

To fix ckeditorfuncnum undefined or null you should add config.filebrowserUploadMethod = 'form' to the config.js file.

CKEDITOR.editorConfig = function( config ) {
    //...
    config.filebrowserUploadMethod = 'form';
};

When adding the config you can get the parameter CKEditorFuncNum return.