diff --git a/.nuget/directxtk12_desktop_2019.nuspec b/.nuget/directxtk12_desktop_2019.nuspec
index 01c9411b..ed8577c6 100644
--- a/.nuget/directxtk12_desktop_2019.nuspec
+++ b/.nuget/directxtk12_desktop_2019.nuspec
@@ -34,7 +34,7 @@ SpriteBatch - simple & efficient 2D sprite rendering
 SpriteFont - bitmap based text rendering
 VertexTypes - structures for commonly used vertex data formats
 WICTextureLoader - WIC-based image file texture loader</description>
-        <releaseNotes>Matches the February 21, 2024 release on GitHub.</releaseNotes>
+        <releaseNotes>Matches the June 4, 2024 release on GitHub.</releaseNotes>
         <projectUrl>http://go.microsoft.com/fwlink/?LinkID=615561</projectUrl>
         <repository type="git" url="https://github.com/microsoft/DirectXTK12.git" />
         <icon>images\icon.jpg</icon>
diff --git a/.nuget/directxtk12_uwp.nuspec b/.nuget/directxtk12_uwp.nuspec
index 346211e1..18d302ba 100644
--- a/.nuget/directxtk12_uwp.nuspec
+++ b/.nuget/directxtk12_uwp.nuspec
@@ -34,7 +34,7 @@ SpriteBatch - simple &amp; efficient 2D sprite rendering
 SpriteFont - bitmap based text rendering
 VertexTypes - structures for commonly used vertex data formats
 WICTextureLoader - WIC-based image file texture loader</description>
-        <releaseNotes>Matches the February 21, 2024 release on GitHub.</releaseNotes>
+        <releaseNotes>Matches the June 4, 2024 release on GitHub.</releaseNotes>
         <projectUrl>http://go.microsoft.com/fwlink/?LinkID=615561</projectUrl>
         <repository type="git" url="https://github.com/microsoft/DirectXTK12.git" />
         <icon>images\icon.jpg</icon>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2ade0058..d2f6eeef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,14 @@ Release available for download on [GitHub](https://github.com/microsoft/DirectXT
 
 ## Release History
 
+### June 4, 2024
+* *breaking change* `CreateUploadBuffer` helper no longer takes initialState parameter as it must be a specific value
+* Renamed Internal namespace to ToolKitInternal for some conformance issues
+* Updated D3DX12 internal copy with latest changes from DirectX-Headers GitHub
+* Add `c_initialRead/UAVTargetState` to help with PC vs. Xbox validation warnings
+* CMake project updates
+* Retired VS 2019 projects for the UWP platform
+
 ### February 21, 2024
 * Project updates for GDK validation
 * Shaders are now built with full path for improved PIX debugging support
diff --git a/CMakeLists.txt b/CMakeLists.txt
index b98c1bcf..7a8640b4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@
 
 cmake_minimum_required (VERSION 3.20)
 
-set(DIRECTXTK12_VERSION 1.5.8)
+set(DIRECTXTK12_VERSION 1.5.9)
 
 if(WINDOWS_STORE OR (DEFINED XBOX_CONSOLE_TARGET))
   set(CMAKE_TRY_COMPILE_TARGET_TYPE "STATIC_LIBRARY")
diff --git a/README.md b/README.md
index 45b897a8..c508f2b3 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ http://go.microsoft.com/fwlink/?LinkID=615561
 
 Copyright (c) Microsoft Corporation.
 
-**February 21, 2024**
+**June 4, 2024**
 
 This package contains the "DirectX Tool Kit", a collection of helper classes for writing Direct3D 12 C++ code for Universal Windows Platform (UWP) apps for Windows 11 and Windows 10, game titles for Xbox Series X\|S and Xbox One, and Win32 desktop applications for Windows 11 and Windows 10.
 
@@ -88,11 +88,13 @@ FOR SECURITY ADVISORIES, see [GitHub](https://github.com/microsoft/DirectXTK12/s
 
 For a full change history, see [CHANGELOG.md](https://github.com/microsoft/DirectXTK12/blob/main/CHANGELOG.md).
 
+* In the June 2024 release, the defaulted parameter `initialState` for the ``CreateUploadBuffer`` function in *BufferHelpers* was removed. Per the DirectX 12 validation layer, the only valid initial state for an upload buffer is ``D3D12_RESOURCE_STATE_GENERIC_READ``.
+
 * Starting with the February 2023 release, the Mouse class implementation of relative mouse movement was updated to accumulate changes between calls to ``GetState``. By default, each time you call ``GetState`` the deltas are reset which works for scenarios where you use relative movement but only call the method once per frame. If you call it more than once per frame, then add an explicit call to ``EndOfInputFrame`` to use an explicit reset model instead.
 
 * As of the September 2022 release, the library makes use of C++11 inline namespaces for differing types that have the same names in the DirectX 11 and DirectX 12 version of the *DirectX Tool Kit*. This provides a link-unique name such as ``DirectX::DX12::SpriteBatch`` that will appear in linker output messages. In most use cases, however, there is no need to add explicit ``DX12`` namespace resolution in client code.
 
-* In the June 2021 release or later, the VS 2019 projects of this library build the HLSL shaders with Shader Model 6 via DXC. Since the NuGet still builds using VS 2017, the build-in shaders in that version are currently Shader Model 5.1. See [this wiki page](https://github.com/microsoft/DirectXTK12/wiki/Shader-Model-6) for more information. The Microsoft GDK projects always use Shader Model 6.
+* Starting with the June 2021 release, this library builds the HLSL shaders with Shader Model 6 via DXC. See [this wiki page](https://github.com/microsoft/DirectXTK12/wiki/Shader-Model-6) for more information. The Microsoft GDK projects have always used Shader Model 6.
 
 * Starting with the June 2020 release, this library makes use of [typed enum bitmask flags](https://walbourn.github.io/modern-c++-bitmask-types/) per the recommendation of the _C++ Standard_ section *17.5.2.1.3 Bitmask types*. This may have *breaking change* impacts to client code: