diff --git a/lib/ably/exceptions.rb b/lib/ably/exceptions.rb
index de2633390..a5b548880 100644
--- a/lib/ably/exceptions.rb
+++ b/lib/ably/exceptions.rb
@@ -38,6 +38,7 @@ def to_s
           additional_info << "base exception: #{@base_exception.class}" if @base_exception
           additional_info << "request_id: #{request_id}" if request_id
           message << "(#{additional_info.join(', ')})"
+          message << "-> see https://help.ably.io/error/#{code} for help" if code
         end
         message.join(' ')
       end
@@ -54,6 +55,8 @@ def as_json(*args)
     # An invalid request was received by Ably
     class InvalidRequest < BaseAblyException; end
 
+    class InvalidCredentials < BaseAblyException; end
+
     # Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided
     class UnauthorizedRequest < BaseAblyException; end
 
diff --git a/lib/ably/models/error_info.rb b/lib/ably/models/error_info.rb
index 8981c0630..7b5494275 100644
--- a/lib/ably/models/error_info.rb
+++ b/lib/ably/models/error_info.rb
@@ -38,7 +38,7 @@ def initialize(hash_object)
       @hash_object     = IdiomaticRubyWrapper(hash_object.clone.freeze)
     end
 
-    %w(message code status_code).each do |attribute|
+    %w(message code href status_code).each do |attribute|
       define_method attribute do
         attributes[attribute.to_sym]
       end
@@ -50,7 +50,8 @@ def attributes
     end
 
     def to_s
-      "<Error: #{message} (code: #{code}, http status: #{status})>"
+      see_msg = " -> see https://help.ably.io/error/#{code} for help" if code
+      "<Error: #{message} (code: #{code}, http status: #{status})>#{see_msg}"
     end
   end
 end
diff --git a/spec/acceptance/realtime/client_spec.rb b/spec/acceptance/realtime/client_spec.rb
index 9df376e47..ff282dd72 100644
--- a/spec/acceptance/realtime/client_spec.rb
+++ b/spec/acceptance/realtime/client_spec.rb
@@ -24,6 +24,22 @@
           end
         end
 
+        context 'with an invalid API key' do
+          let(:custom_logger_object) { TestLogger.new }
+          let(:client) { Ably::Realtime::Client.new(client_options.merge(key: 'app.key:secret', logger: custom_logger_object)) }
+
+          it 'logs an entry with a help href url matching the code #TI5' do
+            client.connect
+            client.connection.once(:failed) do
+              expect(custom_logger_object.logs.find do |severity, message|
+                next unless %w(fatal error).include?(severity.to_s)
+                message.match(%r{https://help.ably.io/error/40400})
+              end).to_not be_nil
+              stop_reactor
+            end
+          end
+        end
+
         context ':tls option' do
           context 'set to false to force a plain-text connection' do
             let(:client_options) { default_options.merge(tls: false, log_level: :none) }
diff --git a/spec/acceptance/rest/client_spec.rb b/spec/acceptance/rest/client_spec.rb
index 575c74000..c7dcae556 100644
--- a/spec/acceptance/rest/client_spec.rb
+++ b/spec/acceptance/rest/client_spec.rb
@@ -27,6 +27,19 @@ def encode64(text)
         end
       end
 
+      context 'with an invalid API key' do
+        let(:client) { Ably::Rest::Client.new(client_options.merge(key: 'app.key:secret', log_level: :fatal)) }
+
+        it 'logs an entry with a help href url matching the code #TI5' do
+          begin
+            client.channels.get('foo').publish('test')
+            raise 'Expected Ably::Exceptions::ResourceMissing'
+          rescue Ably::Exceptions::ResourceMissing => err
+            expect err.to_s.match(%r{https://help.ably.io/error/40400})
+          end
+        end
+      end
+
       context 'with an explicit string :token' do
         let(:client) { Ably::Rest::Client.new(client_options.merge(token: random_str)) }
 
diff --git a/spec/unit/models/error_info_spec.rb b/spec/unit/models/error_info_spec.rb
index 40c2a3653..4b3418f9b 100644
--- a/spec/unit/models/error_info_spec.rb
+++ b/spec/unit/models/error_info_spec.rb
@@ -4,15 +4,25 @@
 describe Ably::Models::ErrorInfo do
   subject { Ably::Models::ErrorInfo }
 
-  it_behaves_like 'a model', with_simple_attributes: %w(code status_code message) do
-    let(:model_args) { [] }
+  context '#TI1, #TI4' do
+    it_behaves_like 'a model', with_simple_attributes: %w(code status_code href message) do
+      let(:model_args) { [] }
+    end
   end
 
-  context '#status' do
+  context '#status #TI1, #TI2' do
     subject { Ably::Models::ErrorInfo.new('statusCode' => 401) }
     it 'is an alias for #status_code' do
       expect(subject.status).to eql(subject.status_code)
       expect(subject.status).to eql(401)
     end
   end
+
+  context 'log entries container help link #TI5' do
+    subject { Ably::Models::ErrorInfo.new('code' => 44444) }
+
+    it 'includes https://help.ably.io/error/[CODE] in the stringified object' do
+      expect(subject.to_s).to include('https://help.ably.io/error/44444')
+    end
+  end
 end