x86 host path on x64/arm64

docs/core/compatibility/3.1.md

@@ -1,7 +1,7 @@
 ---
 title: Breaking changes in .NET Core 3.1
 description: Lists the breaking changes in version 3.1 of .NET Core and ASP.NET Core.
-ms.date: 11/25/2019
+ms.date: 06/22/2022
 ---
 # Breaking changes in .NET Core 3.1
 
@@ -15,6 +15,10 @@ If you're migrating to version 3.1 of .NET Core or ASP.NET Core, the breaking ch
 
 ***
 
+## Deployment
+
+[x86 host path on 64-bit Windows](deployment/7.0/x86-host-path.md)
+
 ## MSBuild
 
 - [Design-time builds only return top-level package references](#design-time-builds-only-return-top-level-package-references)

docs/core/compatibility/6.0.md

@@ -1,7 +1,7 @@
 ---
 title: Breaking changes in .NET 6
 description: Navigate to the breaking changes in .NET 6.
-ms.date: 05/06/2021
+ms.date: 06/22/2022
 no-loc: [Blazor, Razor, Kestrel]
 ---
 # Breaking changes in .NET 6
@@ -89,6 +89,12 @@ For information on other breaking changes for containers in .NET 6, see [.NET 6
 | - | :-: | :-: | - |
 | [CreateEncryptor methods throw exception for incorrect feedback size](cryptography/6.0/cfb-mode-feedback-size-exception.md) | ❌ | ✔️ | Preview 7 |
 
+## Deployment
+
+| Title | Binary compatible | Source compatible | Introduced |
+| - | :-: | :-: | - |
+| [x86 host path on 64-bit Windows](deployment/7.0/x86-host-path.md) | ✔️ | ✔️ | Servicing release |
+
 ## Entity Framework Core
 
 [Breaking changes in EF Core 6](/ef/core/what-is-new/ef-core-6.0/breaking-changes)

docs/core/compatibility/7.0.md

@@ -51,6 +51,7 @@ If you're migrating an app to .NET 7, the breaking changes listed here might aff
 | Title | Binary compatible | Source compatible | Introduced |
 | - | :-: | :-: | - |
 | [Multi-level lookup is disabled](deployment/7.0/multilevel-lookup.md) | ❌ | ✔️ | Preview 4 |
+| [x86 host path on 64-bit Windows](deployment/7.0/x86-host-path.md) | ✔️ | ✔️ | Preview 6 |
 
 ## Extensions
 

docs/core/compatibility/deployment/7.0/x86-host-path.md

@@ -0,0 +1,38 @@
+---
+title: "Breaking change: x86 host path on 64-bit Windows"
+description: Learn about the breaking change in deployment where the 32-bit .NET host isn't added to PATH on 64-bit Windows platforms.
+ms.date: 06/22/2022
+---
+# x86 host path on 64-bit Windows
+
+The x86 versions of .NET installers for Windows have been modified to no longer add the x86 host location (*Program Files (x86)\dotnet*) to the `PATH` environment variable on 64-bit Windows systems.
+
+This change affects .NET Core 3.1, .NET 6, .NET 7, and future versions.
+
+This change only affects the `dotnet` host. It doesn't affect 32-bit/x86 application hosts, like *myapp.exe*. Those hosts will continue to find the x86 runtime correctly (assuming it's installed).
+
+## Previous behavior
+
+The x86 host location was added to `PATH`, even on x64/Arm64 systems. Depending on which .NET architecture installer was run first, a user's machine could have either the native (x64/Arm64) or x86 host listed first in `PATH`.
+
+## New behavior
+
+Going forward, the x86 host location is only added to the `PATH` environment variable on x86 systems.
+
+## Version introduced
+
+.NET 7 Preview 6
+
+## Reason for change
+
+Currently, the x86 host location is added to `PATH`, even on x64/Arm64 systems. Depending on which .NET architecture installer is run first, a user's machine could have either the native (x64/Arm64) or the x86 host as the first location in the `PATH` list. This ambiguity causes problems with the initial .NET installation and during .NET servicing events. Any of these installation scenarios can modify the order of .NET hosts in `PATH`, making it non-deterministic. There's a high chance of behavior regression of the .NET runtime.
+
+This change streamlines the `dotnet` host experience on Windows 64-bit systems. Only 64-bit hosts will be available in the system's `PATH` environment variable: the x64 host on x64 systems and the Arm64 host on Arm64 systems. We removed the ambiguity in the of order of `dotnet` hosts in `PATH`, and only one host will be present.
+
+## Recommended action
+
+If you need the x86 host in the `PATH` environment variable on x64/Arm64 systems, add the host location to `PATH` manually.
+
+## Affected APIs
+
+None.

docs/core/compatibility/toc.yml

@@ -67,6 +67,8 @@ items:
         items:
         - name: Multi-level lookup is disabled
           href: deployment/7.0/multilevel-lookup.md
+        - name: x86 host path on 64-bit Windows
+          href: deployment/7.0/x86-host-path.md
       - name: Extensions
         items:
         - name: ContentRootPath for apps launched by Windows Shell
@@ -211,6 +213,10 @@ items:
         items:
         - name: CreateEncryptor methods throw exception for incorrect feedback size
           href: cryptography/6.0/cfb-mode-feedback-size-exception.md
+      - name: Deployment
+        items:
+        - name: x86 host path on 64-bit Windows
+          href: deployment/7.0/x86-host-path.md
       - name: Entity Framework Core
         href: /ef/core/what-is-new/ef-core-6.0/breaking-changes?toc=/dotnet/core/compatibility/toc.json&bc=/dotnet/breadcrumb/toc.json
       - name: Extensions
@@ -913,6 +919,16 @@ items:
         items:
         - name: Multi-level lookup is disabled
           href: deployment/7.0/multilevel-lookup.md
+        - name: x86 host path on 64-bit Windows
+          href: deployment/7.0/x86-host-path.md
+      - name: .NET 6
+        items:
+        - name: x86 host path on 64-bit Windows
+          href: deployment/7.0/x86-host-path.md
+      - name: .NET Core 3.1
+        items:
+        - name: x86 host path on 64-bit Windows
+          href: deployment/7.0/x86-host-path.md
     - name: Entity Framework Core
       items:
       - name: EF Core 6