Le site ne se charge pas avec 2.4.5 et stable assign

Dans votre app.yml, clonez-vous la branche stable du plugin ?

Oui, comme ceci

hooks:
  after_code:
    - exec:
        cd: $home/plugins
        cmd:
          - git clone https://github.com/discourse/docker_manager.git
          - git clone https://github.com/discourse/discourse-spoiler-alert.git
          - git clone https://github.com/discourse/discourse-styleguide.git
          - git clone --branch stable https://github.com/discourse/discourse-solved.git
          - git clone https://github.com/discourse/discourse-user-notes.git
          - git clone https://github.com/discourse/discourse-checklist.git
          - git clone --branch stable https://github.com/discourse/discourse-assign.git