diff --git a/lib/mailjet/exception/errors.rb b/lib/mailjet/exception/errors.rb
index ef77fb1..fba6a6a 100644
--- a/lib/mailjet/exception/errors.rb
+++ b/lib/mailjet/exception/errors.rb
@@ -55,7 +55,11 @@ def initialize(message = nil, response = nil)
               end
 
       api_message = begin
-        Yajl::Parser.parse(response.response_body)['ErrorMessage']
+        if response.response_body.present?
+          Yajl::Parser.parse(response.response_body)['ErrorMessage']
+         else
+          'Unauthorized'
+        end
       rescue Yajl::ParseError
         response.response_body
       rescue NoMethodError
diff --git a/spec/resources/resource_spec.rb b/spec/resources/resource_spec.rb
index b10e60e..5a7d779 100644
--- a/spec/resources/resource_spec.rb
+++ b/spec/resources/resource_spec.rb
@@ -3,7 +3,7 @@
 RSpec.describe Mailjet::Resource, :vcr do
   context '/invalid_credentials' do
     it 'should raise api connection error' do
-      expect{ Mailjet::Apikey.first }.to raise_error(Mailjet::Unauthorized, /the server responded with status 401 - Invalid Domain or API key/)
+      expect{ Mailjet::Apikey.first }.to raise_error(Mailjet::Unauthorized, /Invalid Domain or API key: Unauthorized/)
     end
   end
 
diff --git a/spec/resources/send_spec.rb b/spec/resources/send_spec.rb
index e8748a1..53a2926 100644
--- a/spec/resources/send_spec.rb
+++ b/spec/resources/send_spec.rb
@@ -68,7 +68,7 @@
           }]
         }
 
-      expect{ described_class.create(message, version: 'v3.1') }.to raise_error(Mailjet::Unauthorized, /the server responded with status 401 - Invalid Domain or API key/)
+      expect{ described_class.create(message, version: 'v3.1') }.to raise_error(Mailjet::Unauthorized, /Visit API keys management section to check your keys/)
     end
   end
 end