dotnet · dotnet-maestro · Dec 11, 2025 · Dec 11, 2025 · Dec 11, 2025 · Dec 11, 2025
diff --git a/.devcontainer/devcontainer.json b/.devcontainer/devcontainer.json
@@ -23,7 +23,6 @@
   "remoteEnv": {
     "PATH": "${containerWorkspaceFolder}/.dotnet:${containerEnv:PATH}",
     "DOTNET_INSTALL_DIR": "${containerWorkspaceFolder}/.dotnet",
-    "DOTNET_MULTILEVEL_LOOKUP": "0",
     "DOTNET_ROOT": "${containerWorkspaceFolder}/.dotnet",
     "DOTNET_MSBUILD_SDK_RESOLVER_CLI_DIR": "${containerWorkspaceFolder}/.dotnet",
     "NUGET_PACKAGES": "/home/vscode/.nuget/packages"

diff --git a/build/RunTestsOnHelix.cmd b/build/RunTestsOnHelix.cmd
@@ -7,7 +7,6 @@ set NUGET_EXPERIMENTAL_NETWORK_RETRY_DELAY_MILLISECONDS=1000
 set MicrosoftNETBuildExtensionsTargets=%HELIX_CORRELATION_PAYLOAD%\ex\msbuildExtensions\Microsoft\Microsoft.NET.Build.Extensions\Microsoft.NET.Build.Extensions.targets
 set DOTNET_ROOT=%HELIX_CORRELATION_PAYLOAD%\d
 set PATH=%DOTNET_ROOT%;%PATH%
-set DOTNET_MULTILEVEL_LOOKUP=0
 set TestFullMSBuild=%1
 
 REM Ensure Visual Studio instances allow preview SDKs

diff --git a/eng/SignCheckExclusionsFile.txt b/eng/SignCheckExclusionsFile.txt
diff --git a/eng/Version.Details.props b/eng/Version.Details.props
diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
diff --git a/eng/common/core-templates/job/job.yml b/eng/common/core-templates/job/job.yml
@@ -73,6 +73,8 @@ jobs:
     templateContext: ${{ parameters.templateContext }}
 
   variables:
+  - name: AllowPtrToDetectTestRunRetryFiles
+    value: true
   - ${{ if ne(parameters.enableTelemetry, 'false') }}:
     - name: DOTNET_CLI_TELEMETRY_PROFILE
       value: '$(Build.Repository.Uri)'

diff --git a/eng/common/core-templates/job/source-build.yml b/eng/common/core-templates/job/source-build.yml
@@ -60,10 +60,10 @@ jobs:
       pool:
         ${{ if eq(variables['System.TeamProject'], 'public') }}:
           name: $[replace(replace(eq(contains(coalesce(variables['System.PullRequest.TargetBranch'], variables['Build.SourceBranch'], 'refs/heads/main'), 'release'), 'true'), True, 'NetCore-Svc-Public' ), False, 'NetCore-Public')]
-          demands: ImageOverride -equals build.ubuntu.2004.amd64
+          demands: ImageOverride -equals build.ubuntu.2204.amd64
         ${{ if eq(variables['System.TeamProject'], 'internal') }}:
           name: $[replace(replace(eq(contains(coalesce(variables['System.PullRequest.TargetBranch'], variables['Build.SourceBranch'], 'refs/heads/main'), 'release'), 'true'), True, 'NetCore1ESPool-Svc-Internal'), False, 'NetCore1ESPool-Internal')]
-          image: 1es-mariner-2
+          image: 1es-azurelinux-3
           os: linux
     ${{ else }}:
       pool:

diff --git a/eng/common/core-templates/job/source-index-stage1.yml b/eng/common/core-templates/job/source-index-stage1.yml
@@ -3,7 +3,7 @@ parameters:
   sourceIndexBuildCommand: powershell -NoLogo -NoProfile -ExecutionPolicy Bypass -Command "eng/common/build.ps1 -restore -build -binarylog -ci"
   preSteps: []
   binlogPath: artifacts/log/Debug/Build.binlog
-  condition: ''
+  condition: eq(variables['Build.SourceBranch'], 'refs/heads/main')
   dependsOn: ''
   pool: ''
   is1ESPipeline: ''
@@ -25,10 +25,10 @@ jobs:
     pool:
       ${{ if eq(variables['System.TeamProject'], 'public') }}:
         name: $(DncEngPublicBuildPool)
-        image: windows.vs2022.amd64.open
+        image: windows.vs2026preview.scout.amd64.open
       ${{ if eq(variables['System.TeamProject'], 'internal') }}:
         name: $(DncEngInternalBuildPool)
-        image: windows.vs2022.amd64
+        image: windows.vs2026preview.scout.amd64
 
   steps:
   - ${{ if eq(parameters.is1ESPipeline, '') }}:
@@ -41,4 +41,4 @@ jobs:
 
   - template: /eng/common/core-templates/steps/source-index-stage1-publish.yml
     parameters:
-      binLogPath: ${{ parameters.binLogPath }}
+      binLogPath: ${{ parameters.binLogPath }}
diff --git a/eng/common/core-templates/steps/install-microbuild.yml b/eng/common/core-templates/steps/install-microbuild.yml
@@ -13,6 +13,8 @@ parameters:
   # Unfortunately, _SignType can't be used to exclude the use of the service connection in non-real sign scenarios. The
   # variable is not available in template expression. _SignType has a very large proliferation across .NET, so replacing it is tough.
   microbuildUseESRP: true
+  # Microbuild installation directory
+  microBuildOutputFolder: $(Agent.TempDirectory)/MicroBuild
   # Microbuild version
   microbuildPluginVersion: 'latest'
 
@@ -27,8 +29,27 @@ steps:
         inputs:
           packageType: sdk
           version: 8.0.x
-          installationPath: ${{ parameters.microBuildOutputFolder }}/.dotnet
-          workingDirectory: ${{ parameters.microBuildOutputFolder }}
+          installationPath: ${{ parameters.microBuildOutputFolder }}/.dotnet-microbuild
+        condition: and(succeeded(), ne(variables['Agent.Os'], 'Windows_NT'))
+
+      - script: |
+          set -euo pipefail
+
+          # UseDotNet@2 prepends the dotnet executable path to the PATH variable, so we can call dotnet directly
+          version=$(dotnet --version)
+          cat << 'EOF' > ${{ parameters.microBuildOutputFolder }}/global.json
+          {
+            "sdk": {
+              "version": "$version",
+              "paths": [
+                "${{ parameters.microBuildOutputFolder }}/.dotnet-microbuild"
+              ],
+              "errorMessage": "The .NET SDK version $version is required to install the MicroBuild signing plugin."
+            }
+          }
+          EOF
+        displayName: 'Add global.json to MicroBuild Installation path'
+        workingDirectory: ${{ parameters.microBuildOutputFolder }}
         condition: and(succeeded(), ne(variables['Agent.Os'], 'Windows_NT'))
 
     - script: |
@@ -68,7 +89,7 @@ steps:
               ConnectedPMEServiceName: 248d384a-b39b-46e3-8ad5-c2c210d5e7ca
         microbuildEnv:
           TeamName: $(_TeamName)
-          MicroBuildOutputFolderOverride: $(Agent.TempDirectory)/MicroBuild
+          MicroBuildOutputFolderOverride: ${{ parameters.microBuildOutputFolder }}
           SYSTEM_ACCESSTOKEN: $(System.AccessToken)
         continueOnError: ${{ parameters.continueOnError }}
         condition: and(succeeded(), eq(variables['Agent.Os'], 'Windows_NT'), in(variables['_SignType'], 'real', 'test'))
@@ -82,6 +103,7 @@ steps:
             zipSources: false
             feedSource: https://dnceng.pkgs.visualstudio.com/_packaging/MicroBuildToolset/nuget/v3/index.json
             version: ${{ parameters.microbuildPluginVersion }}
+            workingDirectory: ${{ parameters.microBuildOutputFolder }}
             ${{ if eq(parameters.microbuildUseESRP, true) }}:
               ConnectedServiceName: 'MicroBuild Signing Task (DevDiv)'
               ${{ if eq(variables['System.TeamProject'], 'DevDiv') }}:
@@ -90,7 +112,7 @@ steps:
                 ConnectedPMEServiceName: c24de2a5-cc7a-493d-95e4-8e5ff5cad2bc
           microbuildEnv:
             TeamName: $(_TeamName)
-            MicroBuildOutputFolderOverride: $(Agent.TempDirectory)/MicroBuild
+            MicroBuildOutputFolderOverride: ${{ parameters.microBuildOutputFolder }}
             SYSTEM_ACCESSTOKEN: $(System.AccessToken)
           continueOnError: ${{ parameters.continueOnError }}
           condition: and(succeeded(), ne(variables['Agent.Os'], 'Windows_NT'),  eq(variables['_SignType'], 'real'))
diff --git a/eng/common/generate-sbom-prep.sh b/eng/common/generate-sbom-prep.sh
diff --git a/eng/common/internal-feed-operations.ps1 b/eng/common/internal-feed-operations.ps1
@@ -26,7 +26,7 @@ function SetupCredProvider {
   $url = 'https://raw.githubusercontent.com/microsoft/artifacts-credprovider/master/helpers/installcredprovider.ps1'
 
   Write-Host "Writing the contents of 'installcredprovider.ps1' locally..."
-  Invoke-WebRequest $url -OutFile installcredprovider.ps1
+  Invoke-WebRequest $url -UseBasicParsing -OutFile installcredprovider.ps1
 
   Write-Host 'Installing plugin...'
   .\installcredprovider.ps1 -Force

diff --git a/eng/common/post-build/nuget-verification.ps1 b/eng/common/post-build/nuget-verification.ps1
@@ -65,7 +65,7 @@ if ($NuGetExePath) {
         Write-Host "Downloading nuget.exe from $nugetExeUrl..."
         $ProgressPreference = 'SilentlyContinue'
         try {
-            Invoke-WebRequest $nugetExeUrl -OutFile $downloadedNuGetExe
+            Invoke-WebRequest $nugetExeUrl -UseBasicParsing -OutFile $downloadedNuGetExe
             $ProgressPreference = 'Continue'
         } catch {
             $ProgressPreference = 'Continue'

diff --git a/eng/common/sdk-task.ps1 b/eng/common/sdk-task.ps1
@@ -70,7 +70,7 @@ try {
       $GlobalJson.tools | Add-Member -Name "vs" -Value (ConvertFrom-Json "{ `"version`": `"16.5`" }") -MemberType NoteProperty
     }
     if( -not ($GlobalJson.tools.PSObject.Properties.Name -match "xcopy-msbuild" )) {
-      $GlobalJson.tools | Add-Member -Name "xcopy-msbuild" -Value "17.14.16" -MemberType NoteProperty
+      $GlobalJson.tools | Add-Member -Name "xcopy-msbuild" -Value "18.0.0" -MemberType NoteProperty
     }
     if ($GlobalJson.tools."xcopy-msbuild".Trim() -ine "none") {
         $xcopyMSBuildToolsFolder = InitializeXCopyMSBuild $GlobalJson.tools."xcopy-msbuild" -install $true

diff --git a/eng/common/tools.ps1 b/eng/common/tools.ps1
@@ -157,9 +157,6 @@ function InitializeDotNetCli([bool]$install, [bool]$createSdkLocationFile) {
     return $global:_DotNetInstallDir
   }
 
-  # Don't resolve runtime, shared framework, or SDK from other locations to ensure build determinism
-  $env:DOTNET_MULTILEVEL_LOOKUP=0
-
   # Disable first run since we do not need all ASP.NET packages restored.
   $env:DOTNET_NOLOGO=1
 
@@ -225,7 +222,6 @@ function InitializeDotNetCli([bool]$install, [bool]$createSdkLocationFile) {
   # Make Sure that our bootstrapped dotnet cli is available in future steps of the Azure Pipelines build
   Write-PipelinePrependPath -Path $dotnetRoot
 
-  Write-PipelineSetVariable -Name 'DOTNET_MULTILEVEL_LOOKUP' -Value '0'
   Write-PipelineSetVariable -Name 'DOTNET_NOLOGO' -Value '1'
 
   return $global:_DotNetInstallDir = $dotnetRoot
@@ -277,7 +273,7 @@ function GetDotNetInstallScript([string] $dotnetRoot) {
 
     Retry({
       Write-Host "GET $uri"
-      Invoke-WebRequest $uri -OutFile $installScript
+      Invoke-WebRequest $uri -UseBasicParsing -OutFile $installScript
     })
   }
 
@@ -394,8 +390,8 @@ function InitializeVisualStudioMSBuild([bool]$install, [object]$vsRequirements =
 
   # If the version of msbuild is going to be xcopied,
   # use this version. Version matches a package here:
-  # https://dev.azure.com/dnceng/public/_artifacts/feed/dotnet-eng/NuGet/Microsoft.DotNet.Arcade.MSBuild.Xcopy/versions/17.14.16
-  $defaultXCopyMSBuildVersion = '17.14.16'
+  # https://dev.azure.com/dnceng/public/_artifacts/feed/dotnet-eng/NuGet/Microsoft.DotNet.Arcade.MSBuild.Xcopy/versions/18.0.0
+  $defaultXCopyMSBuildVersion = '18.0.0'
 
   if (!$vsRequirements) {
     if (Get-Member -InputObject $GlobalJson.tools -Name 'vs') {
@@ -510,7 +506,7 @@ function InitializeXCopyMSBuild([string]$packageVersion, [bool]$install) {
     Write-Host "Downloading $packageName $packageVersion"
     $ProgressPreference = 'SilentlyContinue' # Don't display the console progress UI - it's a huge perf hit
     Retry({
-      Invoke-WebRequest "https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/flat2/$packageName/$packageVersion/$packageName.$packageVersion.nupkg" -OutFile $packagePath
+      Invoke-WebRequest "https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/flat2/$packageName/$packageVersion/$packageName.$packageVersion.nupkg" -UseBasicParsing -OutFile $packagePath
     })
 
     if (!(Test-Path $packagePath)) {
@@ -556,23 +552,30 @@ function LocateVisualStudio([object]$vsRequirements = $null){
     Write-Host "Downloading vswhere $vswhereVersion"
     $ProgressPreference = 'SilentlyContinue' # Don't display the console progress UI - it's a huge perf hit
     Retry({
-      Invoke-WebRequest "https://netcorenativeassets.blob.core.windows.net/resource-packages/external/windows/vswhere/$vswhereVersion/vswhere.exe" -OutFile $vswhereExe
+      Invoke-WebRequest "https://netcorenativeassets.blob.core.windows.net/resource-packages/external/windows/vswhere/$vswhereVersion/vswhere.exe" -UseBasicParsing -OutFile $vswhereExe
     })
   }
 
-  if (!$vsRequirements) { $vsRequirements = $GlobalJson.tools.vs }
+  if (!$vsRequirements) {
+    if (Get-Member -InputObject $GlobalJson.tools -Name 'vs' -ErrorAction SilentlyContinue) {
+      $vsRequirements = $GlobalJson.tools.vs
+    } else {
+      $vsRequirements = $null
+    }
+  }
+
   $args = @('-latest', '-format', 'json', '-requires', 'Microsoft.Component.MSBuild', '-products', '*')
 
   if (!$excludePrereleaseVS) {
     $args += '-prerelease'
   }
 
-  if (Get-Member -InputObject $vsRequirements -Name 'version') {
+  if ($vsRequirements -and (Get-Member -InputObject $vsRequirements -Name 'version' -ErrorAction SilentlyContinue)) {
     $args += '-version'
     $args += $vsRequirements.version
   }
 
-  if (Get-Member -InputObject $vsRequirements -Name 'components') {
+  if ($vsRequirements -and (Get-Member -InputObject $vsRequirements -Name 'components' -ErrorAction SilentlyContinue)) {
     foreach ($component in $vsRequirements.components) {
       $args += '-requires'
       $args += $component

diff --git a/eng/common/tools.sh b/eng/common/tools.sh
@@ -115,9 +115,6 @@ function InitializeDotNetCli {
 
   local install=$1
 
-  # Don't resolve runtime, shared framework, or SDK from other locations to ensure build determinism
-  export DOTNET_MULTILEVEL_LOOKUP=0
-
   # Disable first run since we want to control all package sources
   export DOTNET_NOLOGO=1
 
@@ -166,7 +163,6 @@ function InitializeDotNetCli {
   # build steps from using anything other than what we've downloaded.
   Write-PipelinePrependPath -path "$dotnet_root"
 
-  Write-PipelineSetVariable -name "DOTNET_MULTILEVEL_LOOKUP" -value "0"
   Write-PipelineSetVariable -name "DOTNET_NOLOGO" -value "1"
 
   # return value

diff --git a/eng/common/vmr-sync.ps1 b/eng/common/vmr-sync.ps1
@@ -103,7 +103,7 @@ Set-StrictMode -Version Latest
 Highlight 'Installing .NET, preparing the tooling..'
 . .\eng\common\tools.ps1
 $dotnetRoot = InitializeDotNetCli -install:$true
-$darc = Get-Darc "1.1.0-beta.25514.2"
+$darc = Get-Darc
 $dotnet = "$dotnetRoot\dotnet.exe"
 
 Highlight "Starting the synchronization of VMR.."

diff --git a/eng/common/vmr-sync.sh b/eng/common/vmr-sync.sh
@@ -164,7 +164,7 @@ set -e
 highlight 'Installing .NET, preparing the tooling..'
 source "./eng/common/tools.sh"
 InitializeDotNetCli true
-GetDarc "1.1.0-beta.25514.2"
+GetDarc
 dotnetDir=$( cd ./.dotnet/; pwd -P )
 dotnet=$dotnetDir/dotnet
 

diff --git a/eng/restore-toolset.ps1 b/eng/restore-toolset.ps1
@@ -42,7 +42,6 @@ function CreateBuildEnvScripts()
   $scriptContents = @"
 @echo off
 title SDK Build ($RepoRoot)
-set DOTNET_MULTILEVEL_LOOKUP=0
 REM https://aka.ms/vs/unsigned-dotnet-debugger-lib
 set VSDebugger_ValidateDotnetDebugLibSignatures=0
 
@@ -62,7 +61,6 @@ DOSKEY killdotnet=taskkill /F /IM dotnet.exe /T ^& taskkill /F /IM VSTest.Consol
   $scriptPath = Join-Path $ArtifactsDir "sdk-build-env.ps1"
   $scriptContents = @"
 `$host.ui.RawUI.WindowTitle = "SDK Build ($RepoRoot)"
-`$env:DOTNET_MULTILEVEL_LOOKUP=0
 # https://aka.ms/vs/unsigned-dotnet-debugger-lib
 `$env:VSDebugger_ValidateDotnetDebugLibSignatures=0
 

diff --git a/eng/restore-toolset.sh b/eng/restore-toolset.sh
@@ -54,7 +54,6 @@ function CreateBuildEnvScript {
   scriptPath="$artifacts_dir/sdk-build-env.sh"
   scriptContents="
 #!/usr/bin/env bash
-export DOTNET_MULTILEVEL_LOOKUP=0
 
 export DOTNET_ROOT=$DOTNET_INSTALL_DIR
 export DOTNET_MSBUILD_SDK_RESOLVER_CLI_DIR=$DOTNET_INSTALL_DIR

diff --git a/global.json b/global.json
@@ -7,7 +7,7 @@
     "errorMessage": "The .NET SDK is not installed or is not configured correctly. Please run ./build to install the correct SDK version locally."
   },
   "tools": {
-    "dotnet": "10.0.100-rc.1.25451.107",
+    "dotnet": "10.0.100",
     "runtimes": {
       "dotnet": [
         "$(MicrosoftNETCorePlatformsPackageVersion)"
@@ -21,8 +21,8 @@
     }
   },
   "msbuild-sdks": {
-    "Microsoft.DotNet.Arcade.Sdk": "11.0.0-beta.25521.106",
-    "Microsoft.DotNet.Helix.Sdk": "11.0.0-beta.25521.106",
+    "Microsoft.DotNet.Arcade.Sdk": "11.0.0-beta.25615.104",
+    "Microsoft.DotNet.Helix.Sdk": "11.0.0-beta.25615.104",
     "Microsoft.Build.NoTargets": "3.7.0",
     "Microsoft.Build.Traversal": "3.4.0",
     "Microsoft.WixToolset.Sdk": "5.0.2-dotnet.2811440"

diff --git a/src/BuiltInTools/Watch/HotReload/HotReloadEventSource.cs b/src/BuiltInTools/Watch/HotReload/HotReloadEventSource.cs
@@ -7,7 +7,7 @@
 namespace Microsoft.DotNet.Watch
 {
     [EventSource(Name = "HotReload")]
-    internal sealed class HotReloadEventSource : EventSource
+    internal sealed partial class HotReloadEventSource : EventSource
     {
         public enum StartType
         {

@@ -128,11 +128,11 @@ internal string Layout(int indent = 0)
             {
                 for (int i = 0; i < _columns.Count; ++i)
                 {
-                    b.Append(new string(_settings.HeaderSeparator.Value, _columns[i].CalculatedWidth));
+                    b.Append(_settings.HeaderSeparator.Value, _columns[i].CalculatedWidth);
 
                     if (i < _columns.Count - 1)
                     {
-                        b.Append(new string(' ', _settings.ColumnPadding));
+                        b.Append(' ', _settings.ColumnPadding);
                     }
                 }
                 b.AppendLine().Indent(indent);

diff --git a/src/Cli/dotnet/PerformanceLogEventSource.cs b/src/Cli/dotnet/PerformanceLogEventSource.cs
@@ -12,14 +12,10 @@
 namespace Microsoft.DotNet.Cli;
 
 [EventSource(Name = "Microsoft-Dotnet-CLI-Performance", Guid = "cbd57d06-3b9f-5374-ed53-cfbcc23cf44f")]
-internal sealed class PerformanceLogEventSource : EventSource
+internal sealed partial class PerformanceLogEventSource : EventSource
 {
     internal static PerformanceLogEventSource Log = new();
 
-    private PerformanceLogEventSource()
-    {
-    }
-
     [NonEvent]
     internal void LogStartUpInformation(PerformanceLogStartupInformation startupInfo)
     {