Are you getting an error when you try this or does it just appear unsupported from the docs? What specific google gems are you using so I can try to reproduce the issue here.

@thagomizer I am using the stackdriver gem (version 0.16.1). It just appears unsupported. I have no problem logging, though some logs seem to be missing. I thought maybe it's supported but was not sure because I didn't know how to test it.

Observed in latest stackdriver gem.

If on_error is used in Google::Cloud.configure, it can catch the exceptions raised in the application.

Google::Cloud.configure do |config|
  config.project_id 	  = "<PROJECT_ID>"
  config.credentials    = "key.json"
  config.on_error        = lambda do |error| puts(error) end
end

But if it is used inside Rails config as follows, it is not catching exceptions.
Rails’s environment/*.rb

Rails.application.configure do |config|
  config.google_cloud.project_id    = "<PROJECT_ID>"
  config.google_cloud.credentials  = "key.json"
  config.google_cloud.on_error      = lambda do |error| puts(error) end
  end
end

I have noticed the source codes here [1] and found that on_error is not copied in ErrorReporting (Cloud Trace and Cloud Logging also) for Rails. on_error is then added to the default callback [2] but it is not copied for Rails.

If this behavior is intended and on_error cannot be used in Rails config, please kindly add a note or warning to the READEME [3] as some developers are having trouble with which configuration can be used for Rails config.

[1]