ancm-arm64, installer patches for ASP.NET Core module on Windows 11 ARM64 and IIS.

Background

The official installer for .NET 8.0/9.0 at this moment only properly installs ASP.NET Core module ARM64 bits on the machine, so that only pure ARM64 ASP.NET Core web apps can run on IIS. The application pool simply crashes when you try to host x86 or x64 web apps even if you enable emulation.

.NET Version	Patch Required?	Notes
.NET 10 Preview 2+	❌ No	Already patched by Microsoft; no action needed.
.NET 10 Preview 1	✅ Yes	This patch applies to Preview 1 only.
.NET 8.0 / 9.0	⚠️ Maybe	Microsoft might release patched installers later. Verify carefully if patch is needed.
.NET 7.0	✅ Yes	.NET 7.0 is end-of-life.
.NET 6.0 and below	❌ No	.NET 6.0 and below are end-of-life and only runs in x64/x86 emulation on ARM64.

BTW, I also wrote about my investigation on this topic in details and hope you find the technical details useful when you study Windows ARM64.

Preparation

Perform the following steps to prepare the environment on your development machine,

1. Download the original 64 bit installer from Microsoft.

2. Download WiX Toolset if it isn't installed to %ProgramFilesX86%\WiX Toolset v3.x\bin\.

3. Extract all contents from original Microsoft installer using dark.exe with

   dark.exe dotnet-hosting-7.0.4-win.exe -x .\msi

At this stage, all useful bits can be found in \msi\AttachedContainer folder, such as AspNetCoreModuleV2_*.msi. This folder provides all files are later used for patching.

Note that here we use .NET 7.0.4 as an example. The same approach should apply to other versions (including the latest .NET 10 Preview) till Microsoft officially ships the necessary changes in future releases.

Apply the Patch

1. Execute the official installer to install ARM64 bits to IIS.
2. Clone this repo to your local disk.
3. Execute patch.ps1 -msiFolder <folder> (this points to the AttachedContainer folder in earlier steps) as administrator so that it extracts the necessary files from those MSI packages and install to the desired places.

   Note that this install script also installs a few helper files compiled by me. They are ARM64X pure forwarders required for ARM64/x64 side by side execution. The source code and build script are in src folder.

Restore to Default

1. Execute restore.ps1 as administrator.

You should restore to default before upgrading the hosting bundle to a newer version.