Update qbo_controller.rb

app/controllers/qbo_controller.rb

@@ -32,9 +32,9 @@ class QboController < ApplicationController
   # Called when the user requests that Redmine to connect to QBO
   #
   def authenticate
-    token = Qbo.get_oauth_consumer.get_request_token(:oauth_callback => qbo_oauth_callback_url)
+    callback = quickbooks_oauth_callback_url
+    token = Qbo.get_oauth_consumer.get_request_token(:oauth_callback => callback)
     #session[:qb_request_token] = token
-    # If Rails >= 4.1 you need to do this => 
     session[:qb_request_token] = Marshal.dump(token)
     redirect_to("https://appcenter.intuit.com/Connect/Begin?oauth_token=#{token.token}") and return
   end