Use latest runner images with Mono from Homebrew

.github/workflows/main.yml

@@ -10,11 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [windows-latest, ubuntu-22.04, macos-14]
-        # macOS 14 Sonoma will be deprecated on 2026-07-06 and unsupported on 2026-11-02
-        # https://github.com/actions/runner-images/issues/13518
-        # but it is the last macOS image that comes with Mono preinstalled
-        # https://github.com/actions/runner-images/blob/main/images/macos/macos-14-Readme.md
+        os: [windows-latest, ubuntu-latest, macos-latest]
 
     steps:
       # Prerequisites
@@ -35,6 +31,17 @@ jobs:
       with:
         dotnet-version: '8.0.x'
 
+      # Setup Mono (the runner images no longer include it)
+    - name: Install Mono
+      if: matrix.os != 'windows-latest'
+      run: |
+        if [ "$RUNNER_OS" = Linux ]; then
+          eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"
+          echo "$HOMEBREW_PREFIX/bin" >> "$GITHUB_PATH"
+        fi
+        brew install mono
+        mono --version
+
       # Build & package
     - name: Build
       run: pwsh make.ps1

.vsts-ci.yml

@@ -18,7 +18,7 @@ jobs:
   displayName: Linux (Ubuntu)
   timeoutInMinutes: 180
   pool:
-    vmImage: ubuntu-22.04
+    vmImage: ubuntu-latest
   steps:
   - template: eng/steps.yml
     parameters:
@@ -30,7 +30,7 @@ jobs:
   displayName: macOS
   timeoutInMinutes: 180
   pool:
-    vmImage: macOS-14
+    vmImage: macOS-latest
   steps:
   - template: eng/steps.yml
     parameters:

eng/steps.yml

@@ -39,35 +39,20 @@ steps:
       packageType: 'runtime'
       version: '8.0.x'
 
-  - task: UseDotNet@2
-    displayName: Install .NET 6.0 runtime for testing
-    inputs:
-      packageType: 'runtime'
-      version: '6.0.x'
-
-  # Set Mono version on macOS
-  - ${{ if eq(parameters.os, 'macOS') }}:
-    - task: Bash@3
-      displayName: Set Mono Version
-      inputs:
-        targetType: inline
-        script: |
-          # use Mono 6.4.0 version
-          SYMLINK=6.4.0
-          MONOPREFIX=/Library/Frameworks/Mono.framework/Versions/$SYMLINK
-          echo "##vso[task.setvariable variable=DYLD_FALLBACK_LIBRARY_PATH;]$MONOPREFIX/lib:/lib:/usr/lib:$DYLD_LIBRARY_FALLBACK_PATH"
-          echo "##vso[task.setvariable variable=PKG_CONFIG_PATH;]$MONOPREFIX/lib/pkgconfig:$MONOPREFIX/share/pkgconfig:$PKG_CONFIG_PATH"
-          echo "##vso[task.setvariable variable=PATH;]$MONOPREFIX/bin:$PATH"
+  # Setup Mono (the runner images no longer include it)
+  - ${{ if ne(parameters.os, 'Windows') }}:
+    - bash: |
+        if [ "${{ parameters.os }}" = Linux ]; then
+          eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"
+          echo "##vso[task.prependpath]$HOMEBREW_PREFIX/bin"
+        fi
+        brew install mono
+        mono --version
+      displayName: Install Mono
 
   # Dump version info
-  - task: PowerShell@2
+  - script: dotnet --info
     displayName: Version Information
-    inputs:
-      targetType: inline
-      script: |
-        dotnet --info
-        try { msbuild -version } catch { echo "msbuild not found" }
-        try { mono --version } catch { echo "mono not found" }
 
   - powershell: ./make.ps1
     displayName: Build