diff --git a/.github/workflows/ReleaseNotes.md b/.github/workflows/ReleaseNotes.md
index 7c2ecca2..8b92cf20 100644
--- a/.github/workflows/ReleaseNotes.md
+++ b/.github/workflows/ReleaseNotes.md
@@ -1,32 +1,2 @@
-We have joined the .NET Foundation!
-
-Version 4 comes with a new API so a lot of breaking changes should be expected.
-Checkout the upgrade guide (https://github.com/dotnet/MQTTnet/wiki/Upgrading-guide) for an overview of the changes.
-Checkout the new samples (https://github.com/dotnet/MQTTnet/tree/feature/master/Samples) how to use the new API. The wiki only remains for version 3 of this library.
-
-Preview builds of this library are available at: https://www.myget.org/feed/mqttnet/package/nuget/MQTTnet
-
-* [Core] Improved memory management when working with large payloads.
-* [Core] Added support for .NET 6.0.
-* [Core] nuget packages are now created by MSBuild including more information (i.e. commit hash).
-* [Client] Exposed socket linger state in options.
-* [Client] The OS will now choose the best TLS version to use. It is no longer fixed to 1.3 etc. (thanks to @patagonaa, #1271).
-* [Client] Added support for _ServerKeepAlive_ (MQTTv5).
-* [Client] Exposed user properties and reason string in subscribe result.
-* [Client] Exposed user properties and reason string in unsubscribe result.
-* [Client] Migrated application message handler to a regular .NET event (BREAKING CHANGE!).
-* [Client] The will message is longer a regular application message due to not supported properties by the will message (BREAKING CHANGE!).
-* [Client] Timeouts are no longer handled inside the library. Each method (Connect, Publish etc.) supports a cancellation token so that custom timeouts can and must be used (BREAKING CHANGE!).
-* [Client] Exposed certificate revocation mode on options (@andyolivares).
-* [Server] Exposed socket linger state in options.
-* [Server] Added support for returning individual subscription errors (#80 thanks to @jimch)
-* [Server] Improved topic filter comparisons (support for $).
-* [Server] Added more MQTTv5 response information to all interceptors (BREAKING CHANGE!).
-* [Server] Improved session management for MQTT v5 (#1294, thanks to @logicaloud).
-* [Server] All interceptors and events are migrated from interfaces to simple events. All existing APIs are availble but must be migrated to corresponding events (BREAKING CHANGE!).
-* [Server] Removed all interceptor and event interfaces including the delegate implementations etc. (BREAKING CHANGE!).
-* [Server] Renamed a lot of classes and adjusted namespaces (BREAKING CHANGE!).
-* [Server] Introduced a new queueing approach for internal message process (packet bus).
-* [Server] For security reasons the default endpoint (1883) is no longer enabled by default (BREAKING CHANGE!).
-* [Server] Added support for choosing the cipher suite (thanks to @TimSiefert).
-* [Nuget] Added method summaries etc. to nuget packages (thanks to @SpringHgui).
\ No newline at end of file
+* [Client] Fixed MQTTv5 protocol violation in PUBLISH packets (#1423).
+* [Client] Added missing "WithWill..." methods in _MqttClientOptionsBuilder_.
\ No newline at end of file
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f8767c3c..548826f6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -3,8 +3,7 @@ name: CI
 on: [push, pull_request]
 
 env:
-  ASSEMBLY_VERSION: "4.0.0.${{github.run_number}}"
-  NUGET_VERSION:  "4.0.0.${{github.run_number}}"
+  VERSION: "4.0.1.${{github.run_number}}"
 
 jobs:
   build:
@@ -40,7 +39,7 @@ jobs:
         run: msbuild MQTTnet.sln /t:Restore /p:Configuration="Release" /verbosity:m
 
       - name: Build solution
-        run: msbuild MQTTnet.sln /t:Build /p:Configuration="Release" /verbosity:m /p:FileVersion=${{ env.ASSEMBLY_VERSION }} /p:AssemblyVersion=${{ env.ASSEMBLY_VERSION }} /p:PackageVersion=${{ env.NUGET_VERSION }} /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=${{ github.workspace }}\certificate.snk
+        run: msbuild MQTTnet.sln /t:Build /p:Configuration="Release" /verbosity:m /p:FileVersion=${{ env.VERSION }} /p:AssemblyVersion=${{ env.VERSION }} /p:PackageVersion=${{ env.VERSION }} /p:SignAssembly=true /p:AssemblyOriginatorKeyFile=${{ github.workspace }}\certificate.snk
 
       - name: Collect nuget Packages
         uses: actions/upload-artifact@v2
diff --git a/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs b/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs
index 3ed60a24..d8568770 100644
--- a/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs
+++ b/Source/MQTTnet/Client/Options/MqttClientOptionsBuilder.cs
@@ -393,6 +393,17 @@ namespace MQTTnet.Client
             _options.WillPayload = willPayload;
             return this;
         }
+        
+        public MqttClientOptionsBuilder WithWillPayload(string willPayload)
+        {
+            if (string.IsNullOrEmpty(willPayload))
+            {
+                return WithWillPayload((byte[])null);
+            }
+            
+            _options.WillPayload = Encoding.UTF8.GetBytes(willPayload);
+            return this;
+        }
 
         public MqttClientOptionsBuilder WithWillQualityOfServiceLevel(MqttQualityOfServiceLevel willQualityOfServiceLevel)
         {
@@ -405,5 +416,46 @@ namespace MQTTnet.Client
             _options.WillTopic = willTopic;
             return this;
         }
+
+        public MqttClientOptionsBuilder WithWillRetain(bool willRetain = true)
+        {
+            _options.WillRetain = willRetain;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillContentType(string willContentType)
+        {
+            _options.WillContentType = willContentType;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillCorrelationData(byte[] willCorrelationData)
+        {
+            _options.WillCorrelationData = willCorrelationData;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillResponseTopic(string willResponseTopic)
+        {
+            _options.WillResponseTopic = willResponseTopic;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillPayloadFormatIndicator(MqttPayloadFormatIndicator willPayloadFormatIndicator)
+        {
+            _options.WillPayloadFormatIndicator = willPayloadFormatIndicator;
+            return this;
+        }
+        
+        public MqttClientOptionsBuilder WithWillUserProperty(string name, string value)
+        {
+            if (_options.WillUserProperties == null)
+            {
+                _options.WillUserProperties = new List<MqttUserProperty>();
+            }
+            
+            _options.WillUserProperties.Add(new MqttUserProperty(name, value));
+            return this;
+        }
     }
 }
\ No newline at end of file
diff --git a/Source/MQTTnet/Formatter/V5/MqttV5PropertiesWriter.cs b/Source/MQTTnet/Formatter/V5/MqttV5PropertiesWriter.cs
index 3307b661..6b274bba 100644
--- a/Source/MQTTnet/Formatter/V5/MqttV5PropertiesWriter.cs
+++ b/Source/MQTTnet/Formatter/V5/MqttV5PropertiesWriter.cs
@@ -84,6 +84,11 @@ namespace MQTTnet.Formatter.V5
         {
             // If absent, the Application Message does not expire.
             // This library uses 0 to indicate no expiration.
+            if (value == 0)
+            {
+                return;
+            }
+            
             WriteAsFourByteInteger(MqttPropertyId.MessageExpiryInterval, value);
         }