1. 下载最新版 https://www.redmine.org/releases/redmine-4.2.3.tar.gz
  2. 解压 tar zxvf redmine-4.2.3.tar.gz
  3. 复制3.x的files至redmine-4.2.3
  4. 3.x数据库备份 https://www.redmine.org/projects/redmine/wiki/RedmineBackupRestore
  5. 新建数据库 redmine4
  6. 恢复3.x的数据至数据库redmine4
  7. 使用rvm或rbenv升级ruby至2.7.0
  8. gem install bundle
  9. bundle install –without development test
  10. [可选] bundle install –without development test rmagick
  11. [可选] bundle exec rake generate_secret_token
  12. bundle exec rake db:migrate RAILS_ENV=production
  13. 下载4.x对应的插件放到plugins内
  14. bundle exec rake redmine:plugins:migrate RAILS_ENV=production
  15. 启动