Undefined method `params' for #<Hash>

[severin]

Hi there,

Looking at our NewRelic errors dashboard I notice quite a lot of exceptions that we don't see in Rollbar. Digging a bit deeper they are all raised from requests with non-existent paths that raise a RoutingError.

The relevant code is here: https://github.com/rollbar/rollbar-gem/blob/master/lib/rollbar/middleware/rails/show_exceptions.rb#L10

I'm not too familiar with how rails integrates with rack but to me this code looks intuitively wrong: env is supposed to be a hash and so that line should probably be:

key = 'action_dispatch.show_detailed_exceptions'

if exception.is_a?(ActionController::RoutingError) && env[key]
  scope = ...

(The to_s call on key is also not necessary, since key is always a String)

Here is more context from NewRelic:

[linear]

SDK-363 Undefined method `params' for #<Hash>

[waltjones]

env is expected to be a Rack::Request instance, and the method to call [] directly on it has been removed.
https://github.com/rack/rack/blob/v3.0.8/lib/rack/request.rb#L608-L613

What is the situation that leads to having a hash here instead?

[severin]

@waltjones I dug a bit into it: We are still using Rails 4.2, and the signature of the render_exception method has changed in Rails 5.0: rails/rails@9503e65