The puma restart_command might be incorrect, potential solution is here

[Nick Janetakis]

I don't want to make a release for this fix alone but you may need to change this in config/puma.rb in order to get puma to reload (USR2) correctly. It's already fixed in master and will be in v0.9.3.

For now you can change:
restart_command 'bundle exec puma'

To:
restart_command 'bin/puma'

I am deploying to a self compiled version of ruby (no manager) and bin/puma works correctly.

[Nick Janetakis]

Fixed in v0.9.3. Check the release notes.