This has happened to me in the past.  Typically I restore my Vue.env file(from a previous backup) and this fixes it.  If you don't have a backup delete this file & Vue will create a new one.  Keep in mind if you don't have a backup of this file you will loose your custom settings.

If that doesn't work try the same thing with the Config.env file the results willbe the same as above.

Hope this helps - these solutions came from Technician John Canver at EON.