Breaking change: Document dnx scripts bypassing global.json SDK selection

docs/core/compatibility/10.md

@@ -121,6 +121,7 @@ See [Breaking changes in EF Core 10](/ef/core/what-is-new/ef-core-10.0/breaking-
 | [Default workload configuration from 'loose manifests' to 'workload sets' mode](sdk/10.0/default-workload-config.md) | Behavioral change |
 | [`DefineConstants` for target frameworks not available at evaluation time](sdk/10.0/defineconstants-not-available-at-evaluation.md) | Behavioral change |
 | [Code coverage EnableDynamicNativeInstrumentation defaults to false](sdk/10.0/code-coverage-dynamic-native-instrumentation.md) | Behavioral change |
+| [dnx scripts bypass global.json SDK selection](sdk/10.0/dnx-scripts-bypass-global-json.md) | Behavioral change |
 | [dnx.ps1 file is no longer included in .NET SDK](sdk/10.0/dnx-ps1-removed.md) | Source incompatible |
 | [Double quotes in file-level directives are disallowed](sdk/10.0/file-level-directive-double-quotes.md) | Source incompatible |
 | [`dotnet new sln` defaults to SLNX file format](sdk/10.0/dotnet-new-sln-slnx-default.md) | Behavioral change |

docs/core/compatibility/sdk/10.0/dnx-scripts-bypass-global-json.md

@@ -0,0 +1,42 @@
+---
+title: "Breaking change: dnx scripts bypass global.json SDK selection"
+description: "Learn about the breaking change in .NET 10 SDK 10.0.302 where the dnx and dnx.cmd scripts no longer respect global.json for SDK selection."
+ms.date: 07/05/2026
+ai-usage: ai-assisted
+---
+
+# dnx scripts bypass global.json SDK selection
+
+The `dnx` and `dnx.cmd` scripts no longer use the .NET muxer to select the SDK version. Instead, they find the newest installed SDK and invoke it directly, which bypasses any `global.json` file in the working directory.
+
+## Version introduced
+
+.NET 10 SDK 10.0.302, 10.0.400, and .NET 11 Preview 6
+
+## Previous behavior
+
+Previously, the `dnx` scripts invoked `dotnet dnx`, which relied on the .NET muxer to select the SDK version based on any `global.json` file in the working directory. If `global.json` pinned an SDK version that predated .NET 10, the scripts failed with the following error:
+
+```output
+Unrecognized command or argument 'execute'
+```
+
+## New behavior
+
+Starting in .NET 10 SDK 10.0.302, the `dnx` and `dnx.cmd` scripts use `dotnet --list-sdks` to identify the newest installed SDK. They then invoke `dotnet exec <sdk-path>/dotnet.dll dnx` directly, bypassing the .NET muxer and any `global.json` SDK pinning.
+
+## Type of breaking change
+
+This change is a [behavioral change](../../categories.md#behavioral-change).
+
+## Reason for change
+
+Some .NET CLI commands, including `dnx`, are considered version-independent features that should always run with the newest installed SDK. Relying on `global.json` meant that users who pinned an older SDK version to reduce risk from build-impacting changes also inadvertently broke `dnx`. In folders where a pre-.NET 10 SDK was pinned, the `dnx` command was unavailable, which caused confusing errors and, in some cases, timeouts in tools like Copilot CLI.
+
+## Recommended action
+
+Run `dotnet dnx` explicitly instead of the `dnx` script to restore the previous behavior where the .NET muxer and `global.json` control SDK selection.
+
+## Affected APIs
+
+None.

docs/core/compatibility/toc.yml

@@ -194,6 +194,8 @@ items:
                 href: sdk/10.0/dotnet-cli-stderr-output.md
               - name: .NET tool packaging creates RuntimeIdentifier-specific tool packages
                 href: sdk/10.0/dotnet-tool-pack-publish.md
+              - name: dnx scripts bypass global.json SDK selection
+                href: sdk/10.0/dnx-scripts-bypass-global-json.md
               - name: dnx.ps1 file is no longer included in .NET SDK
                 href: sdk/10.0/dnx-ps1-removed.md
               - name: Double quotes in file-level directives are disallowed

docs/core/tools/dotnet-tool-exec.md

@@ -41,7 +41,7 @@ When you run `dotnet tool exec`, the command:
 This command also exists in two other forms for easier use
 
 * `dotnet dnx` - A hidden alias for `dotnet tool exec` that is used as a way to easily implement the `dnx` script itself
-* `dnx` - A shell script that invokes `dotnet dnx` from the SDK. This script is provided by the installer and is available on `PATH`. It allows for very simple use of tools directly via `dnx <toolname>`.
+* `dnx` - A shell script provided by the installer and available on `PATH`. It allows for very simple use of tools directly via `dnx <toolname>`. Starting in .NET 10 SDK 10.0.302, the script bypasses the .NET muxer and any `global.json` SDK pinning—it finds the newest installed SDK using `dotnet --list-sdks` and invokes it directly. To use `global.json` SDK selection instead, run `dotnet dnx` explicitly.
 
 ## Arguments