Redmine

We use the custom workflow plugin to accomplish this, which lets you add simple scripts that execute before or after save to add custom behavior such as this.

Plugins Directory » Custom Workflows

Thanks for the hint. I will take at a look at the plugin.

Jake Kemme wrote:

We use the custom workflow plugin to accomplish this, which lets you add simple scripts that execute before or after save to add custom behavior such as this.

Plugins Directory » Custom Workflows

If using custom workflow plugin , one can use this code in "before_save"

if @issue.status_id_changed?
  unless @issue.current_journal.nil? #check if the issue has a journal
    if @issue.current_journal.notes.empty? #test if notes has content
      errors.add :base, 'Cannot resolve issue without comment.'
    end
  end
end

https://github.com/anteo/redmine_custom_workflows/issues/57#issuecomment-233430599