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I'm upgrading an app to Rails 6 and after fixing all breaking changes I'm now facing an error when sending emails from background jobs.

I use Sidekiq through ActiveJob and I believe I've added the necessary config changes:

# config/application.rb

...

config.load_defaults 6.0


# config/initializers/new_framework_defaults_6_0.rb

...

Rails.application.config.action_mailer.delivery_job = "ActionMailer::MailDeliveryJob"

I'm sending emails using deliver_later, like: UserMailer.notify(user).deliver_later

One important aspect is that the emails ARE being delivered even though I'm getting the error

Error message:

NameError:
uninitialized constant ActionMailer::MailDeliveryJob
Did you mean?  ActionMailer::DeliveryJob

According to Rollbar the context of the error is ActiveJob::QueueAdapters::SidekiqAdapter::JobWrapper

Any help is appreciated, thanks!

Lucas Moulin
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1 Answers1

12

ActionMailer::MailDeliveryJob is new for rails 6, previously it was called ActionMailer::DeliveryJob (and is still present in rails 6 but with deprecation warning for smoother migration)

Looks like you have a situation when jobs from new rails ended up in a sidekiq worker that is still running previous version. Since emails are actually being delivered - most probably you have workers with both rails versions at the same time. Some workers generate the error and job is retried until it is picked by a worker that finally delivers.

To prevent the error it's better to deploy with action_mailer.delivery_job = "ActionMailer::DeliveryJob", make sure all workers are upgraded (=restarted with new code) and only then remove deprecation warning by switching to MailDeliveryJob.

Vasfed
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  • You're correct! To fix it I deployed the new code and used `ps -aux` to look for old Sidekiq processes, after finding and killing an old process everything started to work without errors. Thanks! – Lucas Moulin Oct 10 '19 at 11:41