Error with OAuth2 gem v 0.5.0 - ruby-on-rails

Question

I get a very opaque error with the following code:
client = OAuth2::Client.new(
"#{FACEBOOK_CONFIG['application_id']}", "#{FACEBOOK_CONFIG['secret_key']}",
:site => 'https://graph.facebook.com'
)
token = OAuth2::AccessToken.new(client, fb_token)
token.get('/me')
when I execute token.get('/me'), I get the following output:
OAuth2::Error Exception: OAuth2::Error
This code works fine with v0.4.1 but fails with v0.5.0
Here is the stack trace:
OAuth2::Error
Rails.root: /Users/myname/Sites/mysite
Application Trace | Framework Trace | Full Trace
oauth2 (0.5.0) lib/oauth2/client.rb:107:in `request'
oauth2 (0.5.0) lib/oauth2/access_token.rb:98:in `request'
oauth2 (0.5.0) lib/oauth2/access_token.rb:105:in `get'
app/models/facebook_session.rb:430:in `get_fb_me'
app/models/facebook_session.rb:45:in `get_fb_user_id'
app/models/facebook_session.rb:258:in `authenticate'
app/controllers/devise/registrations_controller.rb:42:in `create'
actionpack (3.0.3) lib/action_controller/metal/implicit_render.rb:4:in `send_action'
actionpack (3.0.3) lib/abstract_controller/base.rb:151:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/rendering.rb:11:in `process_action'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
activesupport (3.0.3) lib/active_support/callbacks.rb:470:in `_run__664618575269127242__process_action__2116611615142804558__callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:409:in `_run_process_action_callbacks'
activesupport (3.0.3) lib/active_support/callbacks.rb:93:in `run_callbacks'
actionpack (3.0.3) lib/abstract_controller/callbacks.rb:17:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `block in instrument'
activesupport (3.0.3) lib/active_support/notifications/instrumenter.rb:21:in `instrument'
activesupport (3.0.3) lib/active_support/notifications.rb:52:in `instrument'
actionpack (3.0.3) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
actionpack (3.0.3) lib/action_controller/metal/rescue.rb:17:in `process_action'
actionpack (3.0.3) lib/abstract_controller/base.rb:120:in `process'
actionpack (3.0.3) lib/abstract_controller/rendering.rb:40:in `process'
actionpack (3.0.3) lib/action_controller/metal.rb:138:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
actionpack (3.0.3) lib/action_controller/metal.rb:178:in `block in action'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:62:in `dispatch'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:27:in `call'
rack-mount (0.6.14) lib/rack/mount/route_set.rb:148:in `block in call'
rack-mount (0.6.14) lib/rack/mount/code_generation.rb:93:in `block in recognize'
rack-mount (0.6.14) lib/rack/mount/code_generation.rb:82:in `optimized_each'
rack-mount (0.6.14) lib/rack/mount/code_generation.rb:92:in `recognize'
rack-mount (0.6.14) lib/rack/mount/route_set.rb:139:in `call'
actionpack (3.0.3) lib/action_dispatch/routing/route_set.rb:492:in `call'
warden (0.10.7) lib/warden/manager.rb:35:in `block in call'
warden (0.10.7) lib/warden/manager.rb:34:in `catch'
warden (0.10.7) lib/warden/manager.rb:34:in `call'
haml (3.0.25) lib/sass/plugin/rack.rb:41:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/head.rb:14:in `call'
rack (1.2.3) lib/rack/methodoverride.rb:24:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/flash.rb:182:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/session/abstract_store.rb:149:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/cookies.rb:295:in `call'
activerecord (3.0.3) lib/active_record/query_cache.rb:32:in `block in call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/query_cache.rb:28:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:12:in `cache'
activerecord (3.0.3) lib/active_record/query_cache.rb:31:in `call'
activerecord (3.0.3) lib/active_record/connection_adapters/abstract/connection_pool.rb:353:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:46:in `block in call'
activesupport (3.0.3) lib/active_support/callbacks.rb:415:in `_run_call_callbacks'
actionpack (3.0.3) lib/action_dispatch/middleware/callbacks.rb:44:in `call'
rack (1.2.3) lib/rack/sendfile.rb:107:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/remote_ip.rb:48:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/show_exceptions.rb:46:in `call'
railties (3.0.3) lib/rails/rack/logger.rb:13:in `call'
rack (1.2.3) lib/rack/runtime.rb:17:in `call'
activesupport (3.0.3) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
rack (1.2.3) lib/rack/lock.rb:11:in `block in call'
<internal:prelude>:10:in `synchronize'
rack (1.2.3) lib/rack/lock.rb:11:in `call'
actionpack (3.0.3) lib/action_dispatch/middleware/static.rb:30:in `call'
railties (3.0.3) lib/rails/application.rb:168:in `call'
railties (3.0.3) lib/rails/application.rb:77:in `method_missing'
railties (3.0.3) lib/rails/rack/debugger.rb:21:in `call'
railties (3.0.3) lib/rails/rack/log_tailer.rb:14:in `call'
rack (1.2.3) lib/rack/content_length.rb:13:in `call'
rack (1.2.3) lib/rack/handler/webrick.rb:52:in `service'
/Users/myname/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
/Users/myname/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
/Users/myname/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'

Answer 1

I've only used Omniauth recently but it looks like your trace is saying you have something like this in your oauth_helper:
def try_access_token
begin
..
rescue OAuth2::AccessDenied
end
end
If that's the case, try changing OAuth2::AccessDenied to OAuth2::Error. Oauth2::Error provides a .code attribute that you can check to determine if it's an access denied response.
4.1 docs: http://rubydoc.info/gems/oauth2/0.4.1/frames
5.0+ docs: http://rubydoc.info/gems/oauth2/0.5.0/frames

Answer 2

I have the same problem.
Looking at the gem code, it's because the Facebook answer is an HTTP code of 400..599.
when 400..599
e = Error.new(response)
raise e if opts[:raise_errors] || options[:raise_errors]
Sadly, the communication between my server to facebook is using HTTPS, therefore, I haven't been able to intercept the problematic request yet.
UPDATE
I got a 400 error from Facebook :
OAuth "Facebook Platform" "invalid_request" "An active access token must be used to query information about the current user."
UPDATE 2
Interesting discussion here : Facebook access_token invalid?
I ended up rolling oauth2 back to 0.4.1 and my FB login and querying works.