Gem mysql2 seems to be incompatible to MariaDB 10.1
When upgrading 9.3 to 9.4 I'm still getting an error because my MySQL/MariaDB-version seems to be too new for the mysql2 gem you're requiring.
/home/git/gitlab $ sudo -u git -H bundle exec rake db:migrate RAILS_ENV=production
rake aborted!
NameError: uninitialized constant Mysql2::Client::LONG_PASSWORD
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/mysql2-0.3.20/lib/mysql2/client.rb:14:in `default_query_options'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/mysql2-0.3.20/lib/mysql2/client.rb:25:in `initialize'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `new'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/mysql2_adapter.rb:18:in `mysql2_connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:438:in `new_connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:448:in `checkout_new_connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:422:in `acquire_connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:349:in `block in checkout'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:348:in `checkout'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:263:in `block in connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:262:in `connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_adapters/abstract/connection_pool.rb:571:in `retrieve_connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_handling.rb:113:in `retrieve_connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/connection_handling.rb:87:in `connection'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/migration.rb:916:in `initialize'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/migration.rb:823:in `new'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/migration.rb:823:in `up'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/migration.rb:801:in `migrate'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/tasks/database_tasks.rb:137:in `migrate'
/home/git/gitlab/vendor/bundle/ruby/2.4.0/gems/activerecord-4.2.8/lib/active_record/railties/databases.rake:44:in `block (2 levels) in <top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)
MySQL-Version: Ver 15.1 Distrib 10.1.26-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2 Ruby-Version: 2.4.1p111 (2017-03-22 revision 58053) [x86_64-linux] gem mysql2-Version: 0.4.9 (installation run through successfully) GitLab-Version from: GitLab CE 9.3.4 GitLab-Version to: GitLab CE 9.4 (stable branch)
Any ideas how I can finish the upgrade?