dotnet 10.0.106 bottle on macOS arm64 installs truncated Microsoft.AspNetCore.Server.IIS*.dll

[azcion]

brew config AND brew doctor output OR brew gist-logs <formula> link

HOMEBREW_VERSION: 5.1.7
ORIGIN: https://github.com/Homebrew/brew
HEAD: 3aae056b8d072624255bc8fd27febb7f327b2265
Last commit: 4 days ago
Branch: stable
Core tap JSON: 22 Apr 00:08 UTC
Core cask tap JSON: 22 Apr 00:08 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DOWNLOAD_CONCURRENCY: 20
HOMEBREW_EDITOR: vi
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 10
HOMEBREW_NO_COLOR: set
Homebrew Ruby: 4.0.2 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.2_1/bin/ruby
CPU: deca-core 64-bit arm_blizzard_avalanche
Clang: 21.0.0 build 2100
Git: 2.53.0 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 26.4.1-arm64
CLT: 26.4.1.0.1775747724
Xcode: 26.4.1
Metal Toolchain: N/A
Rosetta 2: false

brew doctor:
Your system is ready to brew.

Verification

• My brew doctor output says Your system is ready to brew. and am still able to reproduce my issue.
• I ran brew update and am still able to reproduce my issue.
• I have resolved all warnings from brew doctor and that did not fix my problem.
• I searched for recent similar issues at https://github.com/Homebrew/homebrew-core/issues?q=is%3Aissue and found no duplicates.
• My issue is not about a failure to build a formula from source.

What were you trying to do (and why)?

Install and use Homebrew dotnet (10.0.106) on macOS arm64 for local ASP.NET Core development.

What happened (include all command output)?

After brew install dotnet, IIS-related runtime assemblies under Microsoft.AspNetCore.App/10.0.6 appear truncated compared with official Microsoft runtime-pack binaries:

Homebrew files:

• Microsoft.AspNetCore.Server.IIS.dll: 19,456 bytes
• Microsoft.AspNetCore.Server.IISIntegration.dll: 36,352 bytes

Official runtime-pack files for same version (10.0.6):

• Microsoft.AspNetCore.Server.IIS.dll: 757,560 bytes
• Microsoft.AspNetCore.Server.IISIntegration.dll: 46,352 bytes

SHA256 (Homebrew):

• IIS.dll: 6d6f2bc7639bf866b347ab870f90408122ba9321896238a0b22f40d4ba3702ac
• IISIntegration.dll: adbcf4ee28a0c1bf5813688cd79ae61ad9b28052494dd84359f7f1ba41a56341

SHA256 (official runtime pack):

• IIS.dll: a46be85c7e6f11bb692bc767e1f52dc9bc39c3cb72b04cfbdc05ee5e10d41f0d
• IISIntegration.dll: d63f0e8b8dbf628c3a03a19c87b2e4d43ea7d1340704a05c5803d767b5e50c6b

Runtime symptom in app startup:
System.TypeLoadException: Could not load type 'Microsoft.AspNetCore.Builder.IISServerOptions' from assembly 'Microsoft.AspNetCore.Server.IIS, Version=10.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
at Umbraco.Extensions.UmbracoBuilderExtensions.AddWebServer(IUmbracoBuilder builder)

What did you expect to happen?

brew install dotnet should provide complete/valid runtime assemblies matching official Microsoft 10.0.6 runtime-pack content.

Step-by-step reproduction instructions (by running brew commands)

brew install dotnet
/opt/homebrew/bin/dotnet --info
ls -l /opt/homebrew/Cellar/dotnet/10.0.106/libexec/shared/Microsoft.AspNetCore.App/10.0.6/Microsoft.AspNetCore.Server.IIS*.dll

# Compare with official runtime-pack payload for same version:
curl -fsSL -o runtime.nupkg https://api.nuget.org/v3-flatcontainer/microsoft.aspnetcore.app.runtime.osx-arm64/10.0.6/microsoft.aspnetcore.app.runtime.osx-arm64.10.0.6.nupkg
unzip -q runtime.nupkg runtimes/osx-arm64/lib/net10.0/Microsoft.AspNetCore.Server.IIS.dll runtimes/osx-arm64/lib/net10.0/Microsoft.AspNetCore.Server.IISIntegration.dll
ls -l runtimes/osx-arm64/lib/net10.0/Microsoft.AspNetCore.Server.IIS*.dll

[Shaz666]

Hey, I can try to fix this.

[GunniBusch]

Thanks for the report. I reproduced this and traced it to upstream .NET source-build behavior, not a bottle truncation/download corruption.

What’s happening:

• Homebrew’s dotnet formula builds with --source-build.
• In source-build mode (DotNetBuildSourceOnly=true), ASP.NET Core’s IIS/HttpSys projects conditionally compile stubs (instead of full Windows-server implementations), which removes APIs like Microsoft.AspNetCore.Builder.IISServerOptions.
• That is why Microsoft.AspNetCore.Server.IIS.dll is much smaller in Homebrew source-built SDKs and why TypeLoadException occurs for apps expecting those APIs.

Upstream tracking:

• Some Microsoft.AspNetCore.Server.IIS.dll APIs are not available on source-build dotnet/aspnetcore#63783
• Some Microsoft.AspNetCore.Server.HttpSys.dll APIs are not available on source-build dotnet/aspnetcore#63782
• Related source-build API-diff umbrella: API differences between MSFT and source-built SDKs dotnet/source-build#5344

I also verified this still occurs on dotnet 10.0.107 from Homebrew, while Microsoft’s official distribution contains the full IIS assembly.

So the root cause is an upstream source-build content difference for IIS/HttpSys assemblies.