Let's try this

build.ps1

@@ -362,6 +362,11 @@ try {
 
     $toolsetBuildProj = InitializeToolset
 
+    $sdkPath = [IO.Path]::Combine($env:DOTNET_INSTALL_DIR, 'sdk', '3.1.102')
+    if (!(Test-Path $sdkPath)) {
+        InstallDotNetSdk $dotnetRoot '3.1.102-servicing-014873' -skipNonVersionedFiles $true
+    }
+
     $restore = $tmpRestore
 
     if ($ci) {

build.sh

@@ -316,6 +316,8 @@ restore=true
 
 InitializeToolset
 
+InstallDotNetSdk "$DOTNET_INSTALL_DIR" "3.1.102-servicing-014873"
+
 restore=$_tmp_restore=
 
 if [ "$build_repo_tasks" = true ]; then

eng/common/tools.ps1

@@ -139,6 +139,7 @@ function InitializeDotNetCli([bool]$install) {
         InstallDotNetSdk $dotnetRoot $dotnetSdkVersion
       } else {
         Write-PipelineTelemetryError -Category "InitializeToolset" -Message "Unable to find dotnet with SDK version '$dotnetSdkVersion'"
+        ExitWithExitCode 1
       }
     }
 
@@ -183,7 +184,7 @@ function InstallDotNetSdk([string] $dotnetRoot, [string] $version, [string] $arc
   InstallDotNet $dotnetRoot $version $architecture
 }
 
-function InstallDotNet([string] $dotnetRoot, [string] $version, [string] $architecture = "", [string] $runtime = "", [bool] $skipNonVersionedFiles = $true) {
+function InstallDotNet([string] $dotnetRoot, [string] $version, [string] $architecture = "", [string] $runtime = "", [bool] $skipNonVersionedFiles = $false) {
   $installScript = GetDotNetInstallScript $dotnetRoot
   $installParameters = @{
     Version = $version

eng/common/tools.sh

@@ -143,6 +143,7 @@ function InitializeDotNetCli {
         InstallDotNetSdk "$dotnet_root" "$dotnet_sdk_version"
       else
         Write-PipelineTelemetryError -category 'InitializeToolset' "Unable to find dotnet with SDK version '$dotnet_sdk_version'"
+        ExitWithExitCode 1
       fi
     fi
   fi

global.json

@@ -1,9 +1,9 @@
 {
   "sdk": {
-    "version": "3.1.102-servicing-014873"
+    "version": "3.1.101"
   },
   "tools": {
-    "dotnet": "3.1.102-servicing-014873",
+    "dotnet": "3.1.101",
     "runtimes": {
       "dotnet/x64": [
         "$(MicrosoftNETCoreAppInternalPackageVersion)"