Support .NET Framework 4.6.1

Metadorius · filmor · commit cf0ce2e5f161 · 2026-05-05T21:53:51.000+02:00
diff --git a/AUTHORS.md b/AUTHORS.md
@@ -89,3 +89,4 @@
 -   Ehsan Iran-Nejad ([@eirannejad](https://github.com/eirannejad))
 -   ([@legomanww](https://github.com/legomanww))
 -   ([@gertdreyer](https://github.com/gertdreyer))
+-   Kerbiter ([@Metadorius](https://github.com/Metadorius))
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -10,12 +10,13 @@ This document follows the conventions laid out in [Keep a CHANGELOG][].
 ### Added
 
 -  Support `del obj[...]` for types derived from `IList<T>` and `IDictionary<K, V>`
+-  Support for .NET Framework 4.6.1 (#2701)
 
 ### Changed
 ### Fixed
 
 -  Fixed crash when trying to `del clrObj[...]` for non-arrays
-- ci: properly exclude job (#2542)
+-  ci: properly exclude job (#2542)
 
 ## [3.0.5](https://github.com/pythonnet/pythonnet/releases/tag/v3.0.5) - 2024-12-13
 
diff --git a/doc/source/python.rst b/doc/source/python.rst
@@ -45,7 +45,7 @@ Mono (``mono``)
 
 .NET Framework (``netfx``)
     Default on Windows and also only supported there. Must be at least version
-    4.7.2.
+    4.6.1, with 4.7.2 or later recommended.
 
 .NET Core (``coreclr``)
     Self-contained is not supported, must be at least version 3.1.
diff --git a/setup.py b/setup.py
@@ -127,7 +127,7 @@ def finalize_options(self):
 dotnet_libs = [
     DotnetLib(
         "python-runtime",
-        "src/runtime/Python.Runtime.csproj",
+        "src/compat/Python.Runtime.Compat.csproj",
         output="pythonnet/runtime",
     )
 ]
diff --git a/src/compat/Python.Runtime.Compat.csproj b/src/compat/Python.Runtime.Compat.csproj
@@ -0,0 +1,13 @@
+<!-- A dummy project to force MSBuild to package .NET 4.6.1 requirements -->
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net461</TargetFramework>
+    <OutputType>Library</OutputType>
+    <!-- Don't copy the dummy assembly/pdb to output; we only need the resolved references -->
+    <CopyBuildOutputToOutputDirectory>false</CopyBuildOutputToOutputDirectory>
+    <CopyOutputSymbolsToOutputDirectory>false</CopyOutputSymbolsToOutputDirectory>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\runtime\Python.Runtime.csproj" />
+  </ItemGroup>
+</Project>
diff --git a/src/runtime/Loader.cs b/src/runtime/Loader.cs
@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using System.Text;
 
 namespace Python.Runtime
@@ -12,6 +13,28 @@ public unsafe static int Initialize(IntPtr data, int size)
         {
             try
             {
+                // On .NET Framework, the host is python.exe which has no binding
+                // redirects for netstandard2.0 shims (e.g. RuntimeInformation
+                // Version=0.0.0.0 vs the 4.0.2.0 shim on disk). Binding redirects
+                // via config files can't be injected after AppDomain creation, so
+                // resolve assemblies from our runtime directory directly.
+                // Only needed on .NET Framework; on .NET (Core) this causes
+                // duplicate assembly loads, as .deps.json is respected and
+                // the correct assembly is already found.
+                if (typeof(object).Assembly.GetName().Name == "mscorlib")
+                {
+                    AppDomain.CurrentDomain.AssemblyResolve += (_, args) =>
+                    {
+                        var name = new System.Reflection.AssemblyName(args.Name);
+                        var dir = Path.GetDirectoryName(typeof(Loader).Assembly.Location);
+                        var path = Path.Combine(dir, name.Name + ".dll");
+
+                        return File.Exists(path)
+                            ? System.Reflection.Assembly.LoadFrom(path)
+                            : null;
+                    };
+                }
+
                 var dllPath = Encodings.UTF8.GetString((byte*)data.ToPointer(), size);
 
                 if (!string.IsNullOrEmpty(dllPath))

Original file line number	Diff line number	Diff line change
`@@ -127,7 +127,7 @@ def finalize_options(self):`
`127`	`127`	`dotnet_libs = [`
`128`	`128`	`DotnetLib(`
`129`	`129`	`"python-runtime",`
`130`		`- "src/runtime/Python.Runtime.csproj",`
	`130`	`+ "src/compat/Python.Runtime.Compat.csproj",`
`131`	`131`	`output="pythonnet/runtime",`
`132`	`132`	`)`
`133`	`133`	`]`