“This version is not compatible with Drupal 8.x and should be replaced.”

Question

The below theme files, which are the only files I have in my theme folder called 'Lychee', throw the error (in the 'Uninstalled themes' section of /admin/appearance):

This version is not compatible with Drupal 8.x and should be replaced.

How should I resolve this? I followed this guidance: https://www.drupal.org/node/2349827

lychee.info.yml

name: Lychee
description: 'Mobile first theme.'
type: theme
core: 8.x
libraries:
  - lychee/global-styling
regions:
  - navbar: 'Navigation bar'
  - parallax: Parallax
  - content: Content

lychee.libraries.yml

global-styling:
  version: 1.x
  css:
    theme:
      assets/css/styles.css: {}

Answer 1

Your regions section is slightly off. It should be:

regions:
  navbar: 'Navigation bar'
  parallax: Parallax
  content: Content

Note the removal of the - in front of each region.