dotnet · mthalman · Jan 29, 2026 · Dec 11, 2025 · Dec 11, 2025 · Dec 11, 2025
@@ -72,7 +72,7 @@ parameters:
 # The SDK from its artifacts is copied to $(sourcesPath)/.dotnet
 - name: reuseBuildArtifactsFrom
   type: object
-  default: ''
+  default: []
 
 # Enables usage of the system libraries when building.
 - name: useSystemLibraries
@@ -160,7 +160,7 @@ jobs:
         image: ${{ parameters.container.image }}
         options: $(defaultContainerOptions)
 
-  ${{ if ne(parameters.reuseBuildArtifactsFrom, '') }}:
+  ${{ if gt(length(parameters.reuseBuildArtifactsFrom), 0) }}:
     ${{ if eq(parameters.buildPass, '') }}:
       # For PR builds, skip the stage 2 build if the stage 1 build fails.
       # Otherwise, run the stage 2 build even if the stage 1 build fails so that we can get a complete assessment of the build status.
@@ -172,7 +172,7 @@ jobs:
     ${{ else }}:
       condition: succeeded()
     dependsOn:
-    - ${{ if ne(parameters.reuseBuildArtifactsFrom, '') }}:
+    - ${{ if gt(length(parameters.reuseBuildArtifactsFrom), 0) }}:
       - ${{ parameters.reuseBuildArtifactsFrom }}
   variables:
   - ${{ if eq(variables['System.TeamProject'], 'internal') }}:
@@ -213,6 +213,13 @@ jobs:
   - name: artifactsPrepublishDir
     value: $(Build.ArtifactStagingDirectory)/prepublish
 
+  - name: downloadedArtifactsDir
+    value: $(Agent.TempDirectory)/downloaded-artifacts
+  - name: previouslySourceBuiltSdkDir
+    value: $(Agent.TempDirectory)/previously-source-built-sdk
+  - name: previouslySourceBuiltArtifactsDir
+    value: $(Agent.TempDirectory)/previously-source-built-artifacts
+
   - name: successfulJobArtifactName
     value: $(Agent.JobName)_Artifacts
 
@@ -387,6 +394,26 @@ jobs:
   - checkout: self
     fetchDepth: 1
 
+
+  # Create artifact staging directories upfront to satisfy 1ES templateContext.outputs validation
+  # These directories are referenced in templateContext.outputs which validates paths at job start
+  - ${{ if eq(parameters.targetOS, 'windows') }}:
+    - script: |
+        if not exist "$(Build.ArtifactStagingDirectory)\BuildLogs" mkdir "$(Build.ArtifactStagingDirectory)\BuildLogs"
+        if not exist "$(Build.ArtifactStagingDirectory)\prepublish" mkdir "$(Build.ArtifactStagingDirectory)\prepublish"
+        if not exist "$(Build.ArtifactStagingDirectory)\artifacts" mkdir "$(Build.ArtifactStagingDirectory)\artifacts"
+      displayName: Create artifact staging directories
+      condition: always()
+
+  - ${{ if ne(parameters.targetOS, 'windows') }}:
+    - script: |
+        mkdir -p "$(Build.ArtifactStagingDirectory)/BuildLogs"
+        mkdir -p "$(Build.ArtifactStagingDirectory)/prepublish"
+        mkdir -p "$(Build.ArtifactStagingDirectory)/artifacts"
+      displayName: Create artifact staging directories
+      condition: always()
+
+
   - ${{ if not(parameters.isBuiltFromVmr) }}:
     # Synchronize new content in the VMR during PRs
     - template: /eng/common/templates/steps/vmr-sync.yml@self
@@ -402,7 +429,7 @@ jobs:
       displayName: Export VMR sources
       workingDirectory: $(Build.ArtifactStagingDirectory)
 
-  - ${{ if ne(parameters.reuseBuildArtifactsFrom,'') }}:
+  - ${{ if gt(length(parameters.reuseBuildArtifactsFrom), 0) }}:
     - ${{ each reuseBuildArtifacts in parameters.reuseBuildArtifactsFrom }}:
       - ${{ if eq(parameters.buildSourceOnly, true) }}:
         - template: ../steps/download-artifacts.yml
@@ -412,7 +439,7 @@ jobs:
             downloadFilePatterns: |
               assets/*/Private.SourceBuilt.Artifacts.*.tar.gz
               assets/*/dotnet-sdk-*.tar.gz
-            copyDestination: $(sourcesPath)/prereqs/packages/archive/
+            copyDestination: $(downloadedArtifactsDir)
             flattenDirs: true
 
       - ${{ else }}:
@@ -430,7 +457,7 @@ jobs:
 
   - template: /eng/common/templates/steps/enable-internal-runtimes.yml
 
-  - ${{ if and(parameters.excludeRuntimeDependentJobs, eq(parameters.reuseBuildArtifactsFrom, ''), not(parameters.withPreviousSDK)) }}:
+  - ${{ if and(parameters.excludeRuntimeDependentJobs, eq(length(parameters.reuseBuildArtifactsFrom), 0), not(parameters.withPreviousSDK)) }}:
     - script: |
         source "$(sourcesPath)/eng/download-source-built-archive.sh"
         if [[ $SYSTEM_TEAMPROJECT == "internal" ]]; then
@@ -576,20 +603,90 @@ jobs:
             prepSdk=false
           fi
 
+
+          additionalBuildArgs=""
+
+
+
           if [[ "$prepSdk" == "false" ]]; then
             customPrepArgs="${customPrepArgs} --no-sdk"
-            mkdir -p $(sourcesPath)/.dotnet
-            previousSdkPath="$(sourcesPath)/prereqs/packages/archive/dotnet-sdk-*.tar.gz"
-            eval tar -ozxf "$previousSdkPath" -C "$(sourcesPath)/.dotnet"
-            eval rm -f "$previousSdkPath"
+
+            # Determine where to find the SDK tarball.
+            # Prefer downloadedArtifactsDir (used when reuseBuildArtifactsFrom has items),
+            # but fall back to prereqs/packages/archive when it is not available.
+            sdkSearchDir="$(downloadedArtifactsDir)"
+            fallbackSdkDir="$(Build.SourcesDirectory)/prereqs/packages/archive"
+
+            # If the primary directory does not exist or does not contain an SDK tarball,
+            # fall back to the prereqs/packages/archive location.
+            if [ ! -d "$sdkSearchDir" ] || ! find "$sdkSearchDir" -name "dotnet-sdk-*.tar.gz" -print -quit >/dev/null 2>&1; then
+              echo "Primary SDK directory '$sdkSearchDir' is not usable. Falling back to '$fallbackSdkDir'."
+              sdkSearchDir="$fallbackSdkDir"
+            fi
+
+            # After fallback, ensure we have a directory to search.
+            if [ ! -d "$sdkSearchDir" ]; then
+              echo "##vso[task.logissue type=error]SDK extraction required but neither '$(downloadedArtifactsDir)' nor '$fallbackSdkDir' exists."
+              echo "Checking Pipeline Workspace content:"
+              ls -R "$(Pipeline.Workspace)" || true
+              exit 1
+            fi
+
+            previousSdkPath=$(find "$sdkSearchDir" -name "dotnet-sdk-*.tar.gz" | head -n 1)
+
+            if [ -z "$previousSdkPath" ]; then
+              echo "##vso[task.logissue type=error]dotnet-sdk-*.tar.gz not found in '$sdkSearchDir'."
+              echo "Contents of '$sdkSearchDir':"
+              ls -R "$sdkSearchDir" || true
+              exit 1
+            fi
+
+            echo "Found SDK tarball: $previousSdkPath"
+            echo "Extracting SDK..."
+            mkdir -p "$(previouslySourceBuiltSdkDir)"
+            eval tar -xzf "$previousSdkPath" -C "$(previouslySourceBuiltSdkDir)"
+
+            customPrepArgs="${customPrepArgs} --with-sdk $(previouslySourceBuiltSdkDir)"
+            additionalBuildArgs="--with-sdk $(previouslySourceBuiltSdkDir)"
+          fi
+
+          if [[ '${{ length(parameters.reuseBuildArtifactsFrom) }}' -gt '0' ]]; then
+             # Verify download directory exists
+             if [ ! -d "$(downloadedArtifactsDir)" ]; then
+               echo "##vso[task.logissue type=error]Package extraction required but '$(downloadedArtifactsDir)' does not exist."
+               echo "Checking Pipeline Workspace content:"
+               ls -R "$(Pipeline.Workspace)" || true
+               exit 1
+             fi
+
+             artifactsTarball=$(find "$(downloadedArtifactsDir)" -name "Private.SourceBuilt.Artifacts.*.tar.gz" | head -n 1)
+
+             if [ -z "$artifactsTarball" ]; then
+               echo "##vso[task.logissue type=error]Private.SourceBuilt.Artifacts.*.tar.gz not found in $(downloadedArtifactsDir)"
+               echo "Contents of downloaded artifacts:"
+               ls -R "$(downloadedArtifactsDir)"
+               exit 1
+             fi
+
+             echo "Found Artifacts tarball: $artifactsTarball"
+             echo "Extracting artifacts..."
+             mkdir -p "$(previouslySourceBuiltArtifactsDir)"
+             tar -xzf "$artifactsTarball" -C "$(previouslySourceBuiltArtifactsDir)"
+
+             customPrepArgs="${customPrepArgs} --with-packages $(previouslySourceBuiltArtifactsDir)"
+             additionalBuildArgs="${additionalBuildArgs} --with-packages $(previouslySourceBuiltArtifactsDir)"
+          fi
+
+          echo "Prep arguments: $customPrepArgs"
+          echo "Additional build arguments: $additionalBuildArgs"
 
-            echo "##vso[task.setvariable variable=additionalBuildArgs]--with-sdk $(sourcesPath)/.dotnet"
+          if [[ -n "$additionalBuildArgs" ]]; then
+            echo "##vso[task.setvariable variable=additionalBuildArgs]$additionalBuildArgs"
           fi
 
           ./prep-source-build.sh $customPrepArgs
         displayName: Prep the Build
         workingDirectory: $(sourcesPath)
-
     - ${{ if ne(parameters.skipBuild, 'true') }}:
 
       - script: |
@@ -613,7 +710,6 @@ jobs:
               # Set up for signing source-built artifacts post-build.
               extraBuildProperties="$extraBuildProperties /p:DotNetSourceOnlyPostBuildSign=true"
             fi
-
             if [[ '${{ parameters.excludeRuntimeDependentJobs }}' == 'True' ]]; then
               customBuildArgs="$customBuildArgs --with-shared-components $(sharedComponentsDir)"
             fi
@@ -664,9 +760,11 @@ jobs:
 
           buildArgs="$(additionalBuildArgs) $customBuildArgs $extraBuildProperties"
 
-          for envVar in $customEnvVars; do
-            customEnvVarsWithBashSyntax="$customEnvVarsWithBashSyntax export $envVar;"
-          done
+          if [[ -n "$customEnvVars" ]]; then
+            for envVar in $customEnvVars; do
+              customEnvVarsWithBashSyntax="$customEnvVarsWithBashSyntax export $envVar;"
+            done
+          fi
 
           eval $customEnvVarsWithBashSyntax
           $customPreBuildArgs ./build.sh $buildArgs

@@ -183,10 +183,10 @@ function BootstrapArtifacts {
   rm -rf "$workingDir"
 }
 
-# Attempting to bootstrap without an SDK will fail. So either the --no-sdk flag must be passed
-# or a pre-existing .dotnet SDK directory must exist.
-if [ "$buildBootstrap" == true ] && [ "$installDotnet" == false ] && [ ! -d "$REPO_ROOT/.dotnet" ]; then
-  echo "  ERROR: --no-sdk requires --no-bootstrap or a pre-existing .dotnet SDK directory.  Exiting..."
+# Attempting to bootstrap without an SDK will fail. So either the --no-sdk flag must be passed,
+# a pre-existing .dotnet SDK directory must exist, or a custom SDK must be provided via --with-sdk.
+if [ "$buildBootstrap" == true ] && [ "$installDotnet" == false ] && [ ! -d "$REPO_ROOT/.dotnet" ] && [ -z "$customSdkDir" ]; then
+  echo "  ERROR: --no-sdk requires --no-bootstrap, a pre-existing .dotnet SDK directory, or --with-sdk.  Exiting..."
   exit 1
 fi