[BUG]: UseDotNet@2 crashes on a Windows ARM64 host

[simonpolan]

New issue checklist

• I searched for existing GitHub issues
• I read pipeline troubleshooting guide
• I checked how to collect logs

Task name

UseDotNet

Task version

2

Issue Description

Azure DevOps UseDotNet@2 task does crash on Windows 11 ARM64 host.

Exception:
Architecture not supported. If you think this is a bug, please report it at https://github.com/dotnet/cli/issues
##[error]Failed while detecting machine OS platform with error: undefined
At C:\agent_work_tasks\UseDotNet_b0ce7256-7898-45d3-9cb5-176b752bfea6\2.263.0\externals\get-os-platform.ps1:13

Environment type (Please select at least one enviroment where you face this issue)

• Self-Hosted
• Microsoft Hosted
• VMSS Pool
• Container

Azure DevOps Server type

dev.azure.com (formerly visualstudio.com)

Azure DevOps Server Version (if applicable)

No response

Operation system

Windows 11 ARM64

Relevant log output

2025-11-13T10:17:32.0918584Z ##[section]Starting: Use .NET Core sdk 8.x
2025-11-13T10:17:32.0928658Z ==============================================================================
2025-11-13T10:17:32.0928738Z Task         : Use .NET Core
2025-11-13T10:17:32.0928791Z Description  : Acquires a specific version of the .NET Core SDK from the internet or the local cache and adds it to the PATH. Use this task to change the version of .NET Core used in subsequent tasks. Additionally provides proxy support.
2025-11-13T10:17:32.0928842Z Version      : 2.263.0
2025-11-13T10:17:32.0928893Z Author       : Microsoft Corporation
2025-11-13T10:17:32.0928939Z Help         : https://aka.ms/AA4xgy0
2025-11-13T10:17:32.0928986Z ==============================================================================
2025-11-13T10:17:33.0579480Z Tool to install: .NET Core sdk version 8.x.
2025-11-13T10:17:33.2096336Z Found version 8.0.416 in channel 8.0 for user specified version spec: 8.x
2025-11-13T10:17:33.2247585Z Version 8.0.416 was not found in cache.
2025-11-13T10:17:33.2247835Z Getting URL to download .NET Core sdk version: 8.0.416.
2025-11-13T10:17:33.2247998Z Detecting OS platform to find correct download package for the OS.
2025-11-13T10:17:33.2248265Z [command]C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoLogo -Sta -NoProfile -NonInteractive -ExecutionPolicy Unrestricted -Command "& 'C:\agent\_work\_tasks\UseDotNet_b0ce7256-7898-45d3-9cb5-176b752bfea6\2.263.0\externals\get-os-platform.ps1'"
2025-11-13T10:17:33.6279796Z Architecture not supported. If you think this is a bug, please report it at https://github.com/dotnet/cli/issues
2025-11-13T10:17:33.6298354Z ##[error]Failed while detecting machine OS platform with error: undefined
2025-11-13T10:17:33.6322887Z At C:\agent\_work\_tasks\UseDotNet_b0ce7256-7898-45d3-9cb5-176b752bfea6\2.263.0\externals\get-os-platform.ps1:13 
2025-11-13T10:17:33.6323061Z char:19
2025-11-13T10:17:33.6323227Z + ...   default { throw "Architecture not supported. If you think this is a ...
2025-11-13T10:17:33.6323435Z +                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2025-11-13T10:17:33.6323618Z     + CategoryInfo          : OperationStopped: (Architecture no...tnet/cli/issues:String) [], RuntimeException
2025-11-13T10:17:33.6323802Z     + FullyQualifiedErrorId : Architecture not supported. If you think this is a bug, please report it at https://gith 
2025-11-13T10:17:33.6324444Z    ub.com/dotnet/cli/issues
2025-11-13T10:17:33.6324671Z  
2025-11-13T10:17:33.6404263Z ##[section]Finishing: Use .NET Core sdk 8.x

Full task logs with system.debug enabled

No response

Repro steps

Run an Azure DevOps pipeline with the UseDotNet@2 task on a Windows ARM64 host.

[MichelZ]

Have a look at related PR #20695 and issue #20300

[simonpolan]

Have a look at related PR #20695 and issue #20300

@MichelZ Looks great! It would solve both of our issues.