I was just about to post the same problem - for the meantime I'm using Internet Explorer, rather than Edge, while editing my pages.

ckeditor is not part of mojoportal, it can be installed or updated independently of mojoportal.

basic steps

• download the latest version along with whatever plugins you like to use, usually I download it with full default plugins but there are usually a few more needed that I have to download separately. often there are new versions of plugins that go with new versions of ckeditor but not always, sometimes you can just copy any missing plugins from the previous version
   
• put the new ckeditor folder below ~/ClientScript/ and rename it as ckeditorxxx where xxx represents the version, this is just so you remember which version is installed.
   
• you will definitely want the mojofiledrop plugin so copy that from the plugins folder in your current site installation and put it in the plugins folder for the new version of ckeditor
   
• probably want to compare the plugins folder in the new one vs the previous version you were using and download the newest version of any plugins that are missing in the new folder or copy them from the previous version and maybe they still work.
   
• in web.config or user.onfig update the setting to point to your newly created folder:
  <add key="CKEditor:BasePath" value="~/ClientScript/ckeditorxxx/" /> 
   
• toolbars and plugins are also configured in the file /ClientScript/ckeditor-mojoconfig.js
  you can easily add or remove plugins by copying that file with a new name and then point to your copy by changing this setting:<add key="CKEditor:ConfigPath" value="~/ClientScript/ckeditor-mojoconfig.js" />
   
• you may need to use web browser debug tools such as the javascript console to look for any errors. For example if the config file toolbars use plugins that don't exist on disk it may cause the editor to fail to load or it may log an error in the console that will give you a clue about missing plugins or what is wrong in the configuration.