undefined method `eager_autoload!' for Mail:Module

[KeithP]

ruby 2.7.0
rails 6.1.6.1
mail 2.8.0

config/environments/production.rb :

config.eager_load = true

exception :

[21756] ! Unable to start worker
[21756] undefined method eager_autoload!' for Mail:Module [21756] /var/app/current/vendor/bundle/ruby/2.7.0/gems/actionmailer-6.1.6.1/lib/action_mailer.rb:61:in eager_load!'
/var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/application/finisher.rb:134:in each' /var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/application/finisher.rb:134:in block in module:Finisher'
/var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/initializable.rb:32:in instance_exec' /var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/initializable.rb:32:in run'
/var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/initializable.rb:61:in block in run_initializers' /opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:228:in block in tsort_each'
/opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:350:in block (2 levels) in each_strongly_connected_component' /opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:431:in each_strongly_connected_component_from'
/opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:349:in block in each_strongly_connected_component' /opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:347:in each'
/opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:347:in call' /opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:347:in each_strongly_connected_component'
/opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:226:in tsort_each' /opt/rubies/ruby-2.7.7/lib/ruby/2.7.0/tsort.rb:205:in tsort_each'
/var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/initializable.rb:60:in run_initializers' /var/app/current/vendor/bundle/ruby/2.7.0/gems/railties-6.1.6.1/lib/rails/application.rb:391:in initialize!'
/var/app/current/config/environment.rb:6:in <top (required)>' config.ru:3:in require_relative'
config.ru:3:in block in <main>' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/rack/builder.rb:186:in instance_eval'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/rack/builder.rb:186:in initialize' config.ru:in new'
config.ru:in <main>' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/rack/builder.rb:172:in eval'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/rack/builder.rb:172:in new_from_string' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/rack/builder.rb:163:in parse_file'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/configuration.rb:364:in load_rackup' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/configuration.rb:286:in app'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/runner.rb:169:in app' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/runner.rb:173:in start_server'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster/worker.rb:60:in run' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:208:in worker'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:101:in block in spawn_worker' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:101:in fork'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:101:in spawn_worker' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:83:in block in spawn_workers'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:76:in times' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:76:in spawn_workers'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:165:in check_workers' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cluster.rb:438:in run'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/launcher.rb:186:in run' /opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/lib/puma/cli.rb:75:in run'
/opt/rubies/ruby-2.7.7/lib/ruby/gems/2.7.0/gems/puma-6.0.0/bin/puma:10:in <top (required)>' /opt/elasticbeanstalk/.rbenv/versions/2.7.7/bin/puma:25:in load'
/opt/elasticbeanstalk/.rbenv/versions/2.7.7/bin/puma:25:in `

'

with mail 2.7.1, it works fine

[thekendalmiller]

We were also hitting this. While troubleshooting, the error would match the original post above, but also sometimes it would be

[29716] Early termination of worker
[29719] ! Unable to start worker
[29719] uninitialized constant Mail::TestMailer
Did you mean?  SystemMailer
[29719] /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/delivery_methods.rb:42:in `<module:ClassMethods>'
    /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/delivery_methods.rb:40:in `<module:DeliveryMethods>'
    /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/delivery_methods.rb:8:in `<module:ActionMailer>'
    /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/delivery_methods.rb:5:in `<top (required)>'
    /var/app/bundle/ruby/2.7.0/gems/zeitwerk-2.6.6/lib/zeitwerk/kernel.rb:38:in `require'
    /var/app/bundle/ruby/2.7.0/gems/zeitwerk-2.6.6/lib/zeitwerk/kernel.rb:38:in `require'
    /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/base.rb:438:in `<class:Base>'
    /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/base.rb:437:in `<module:ActionMailer>'
    /var/app/bundle/ruby/2.7.0/gems/actionmailer-6.1.7/lib/action_mailer/base.rb:12:in `<top (required)>'
    /var/app/bundle/ruby/2.7.0/gems/zeitwerk-2.6.6/lib/zeitwerk/kernel.rb:38:in `require'
    /var/app/bundle/ruby/2.7.0/gems/zeitwerk-2.6.6/lib/zeitwerk/kernel.rb:38:in `require'
    /var/app/current/app/mailers/application_mailer.rb:1:in `<top (required)>'

ruby 2.7.7
rails 6.1.7
mail 2.8.0

[chitty]

We also ran into this issue, and found it was caused by the incorrect file permissions in 2.8.0 bug. Pinning mail version to 2.7.1 fixed it.

[eval]

Closing as this was related to the permission problem which is fixed as of v2.8.0.1.