PowerShell · adityapatwardhan · Dec 10, 2019 · Nov 19, 2019 · Nov 19, 2019 · Nov 21, 2019
diff --git a/src/System.Management.Automation/engine/Modules/ImportModuleCommand.cs b/src/System.Management.Automation/engine/Modules/ImportModuleCommand.cs
@@ -1881,13 +1881,22 @@ protected override void ProcessRecord()
 
         internal override IList<PSModuleInfo> ImportModulesUsingWinCompat(IEnumerable<string> moduleNames, IEnumerable<ModuleSpecification> moduleFullyQualifiedNames, ImportModuleOptions importModuleOptions)
         {
+            IList<PSModuleInfo> moduleProxyList = new List<PSModuleInfo>();
+#if !UNIX
+            var winPSVersionString = Utils.GetWindowsPowerShellVersionFromRegistry();
+            if (!winPSVersionString.StartsWith("5.1", StringComparison.OrdinalIgnoreCase))
+            {
+                string errorMessage = string.Format(CultureInfo.InvariantCulture, Modules.WinCompatRequredVersionError, winPSVersionString);
+                throw new InvalidOperationException(errorMessage);
+            }
+
             PSSession WindowsPowerShellCompatRemotingSession = CreateWindowsPowerShellCompatResources();
             if (WindowsPowerShellCompatRemotingSession == null)
             {
                 return new List<PSModuleInfo>();
             }
 
-            var moduleProxyList = ImportModule_RemotelyViaPsrpSession(importModuleOptions, moduleNames, moduleFullyQualifiedNames, WindowsPowerShellCompatRemotingSession, usingWinCompat: true);
+            moduleProxyList = ImportModule_RemotelyViaPsrpSession(importModuleOptions, moduleNames, moduleFullyQualifiedNames, WindowsPowerShellCompatRemotingSession, usingWinCompat: true);
             foreach(PSModuleInfo moduleProxy in moduleProxyList)
             {
                 moduleProxy.IsWindowsPowerShellCompatModule = true;
@@ -1896,7 +1905,7 @@ internal override IList<PSModuleInfo> ImportModulesUsingWinCompat(IEnumerable<st
                 string message = StringUtil.Format(Modules.WinCompatModuleWarning, moduleProxy.Name, WindowsPowerShellCompatRemotingSession.Name);
                 WriteWarning(message);
             }
-
+#endif
             return moduleProxyList;
         }
 

diff --git a/src/System.Management.Automation/engine/Utils.cs b/src/System.Management.Automation/engine/Utils.cs
@@ -476,6 +476,41 @@ internal static string GetApplicationBaseFromRegistry(string shellId)
 
             return null;
         }
+
+        private static string s_windowsPowerShellVersion = null;
+
+        /// <summary>
+        /// Get the Windows PowerShell version from registry.
+        /// </summary>
+        /// <returns>
+        /// String of Windows PowerShell version from registry.
+        /// </returns>
+        internal static string GetWindowsPowerShellVersionFromRegistry()
+        {
+            if (!string.IsNullOrEmpty(InternalTestHooks.TestWindowsPowerShellVersionString))
+            {
+                return InternalTestHooks.TestWindowsPowerShellVersionString;
+            }
+
+            if (s_windowsPowerShellVersion != null)
+            {
+                return s_windowsPowerShellVersion;
+            }
+
+            string engineKeyPath = RegistryStrings.MonadRootKeyPath + "\\" +
+                PSVersionInfo.RegistryVersionKey + "\\" + RegistryStrings.MonadEngineKey;
+
+            using (RegistryKey engineKey = Registry.LocalMachine.OpenSubKey(engineKeyPath))
+            {
+                if (engineKey != null)
+                {
+                    s_windowsPowerShellVersion = engineKey.GetValue(RegistryStrings.MonadEngine_MonadVersion) as string;
+                    return s_windowsPowerShellVersion;
+                }
+            }
+
+            return string.Empty;
+        }
 #endif
 
         internal static string DefaultPowerShellAppBase => GetApplicationBase(DefaultPowerShellShellID);
@@ -2066,6 +2101,9 @@ public static class InternalTestHooks
         // since we can't manipulate the System32 directory in a test
         internal static string TestWindowsPowerShellPSHomeLocation;
 
+        // A version of Windows PS that is installed on the system; normally this is retrieved from a reg key that is write-protected.
+        internal static string TestWindowsPowerShellVersionString;
+
         internal static bool ShowMarkdownOutputBypass;
 
         /// <summary>This member is used for internal test purposes.</summary>

@@ -1160,8 +1160,9 @@ private List<RemoteRunspace> CreateRunspacesForUseWindowsPowerShellParameterSet(
 
             NewProcessConnectionInfo connectionInfo = new NewProcessConnectionInfo(this.Credential);
             connectionInfo.AuthenticationMechanism = this.Authentication;
+#if !UNIX
             connectionInfo.PSVersion = new Version(5, 1);
-
+#endif
             var typeTable = TypeTable.LoadDefaultTypeFiles();
             string runspaceName = GetRunspaceName(0, out int runspaceIdUnused);
             remoteRunspaces.Add(RunspaceFactory.CreateRunspace(connectionInfo: connectionInfo,

diff --git a/src/System.Management.Automation/resources/Modules.resx b/src/System.Management.Automation/resources/Modules.resx
@@ -513,6 +513,9 @@
   <data name="WinCompatModuleWarning" xml:space="preserve">
     <value>Module {0} is loaded in Windows PowerShell using {1} remoting session; please note that all input and output of commands from this module will be deserialized objects. If you want to load this module into PowerShell Core please use 'Import-Module -SkipEditionCheck' syntax.</value>
   </data>
+  <data name="WinCompatRequredVersionError" xml:space="preserve">
+    <value>Detected Windows PowerShell version {0}. Windows PowerShell 5.1 is required to load modules using Windows PowerShell compatibility feature. Install Windows Management Framework (WMF) 5.1 from https://aka.ms/WMF5Download to enable this feature.</value>
+  </data>
   <data name="PsModuleOverCimSessionError" xml:space="preserve">
     <value>The module {0} cannot be imported over a CimSession. Try using the PSSession parameter of the Import-Module cmdlet.</value>
   </data>

diff --git a/test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1 b/test/powershell/Modules/Microsoft.PowerShell.Core/CompatiblePSEditions.Module.Tests.ps1
@@ -246,7 +246,16 @@ Describe "Import-Module from CompatiblePSEditions-checked paths" -Tag "CI" {
         New-TestModules -TestCases $successCases -BaseDir $basePath
         New-TestModules -TestCases $failCases -BaseDir $basePath
 
-        $allModules = ($successCases + $failCases).ModuleName
+        $allCases = $successCases + $failCases
+        $allModules = $allCases.ModuleName
+        $versionTestCases = @()
+        foreach($versionString in @('1.0','2.0','3.0','4.0','5.0','5.1','5.1.14393.0'))
+        {
+            foreach($case in $allCases)
+            {
+                $versionTestCases += $case + @{WinPSVersion = $versionString}
+            }
+        }
 
         # make sure there are no ImplicitRemoting leftovers from previous tests
         Get-Module | Where-Object {$_.PrivateData.ImplicitRemoting} | Remove-Module -Force
@@ -300,6 +309,24 @@ Describe "Import-Module from CompatiblePSEditions-checked paths" -Tag "CI" {
             Import-Module $ModuleName -UseWindowsPowerShell -Force
             & "Test-${ModuleName}PSEdition" | Should -Be 'Desktop'
         }
+
+        It "WinCompat works only with Windows PS 5.1 (when PSEdition <Editions> and WinPSVersion <WinPSVersion>)" -TestCases $versionTestCases -Skip:(-not $IsWindows) {
+            param($Editions, $ModuleName, $Result, $WinPSVersion)
+
+            try {
+                [System.Management.Automation.Internal.InternalTestHooks]::SetTestHook("TestWindowsPowerShellVersionString", $WinPSVersion)
+                if ($WinPSVersion.StartsWith('5.1')) {
+                    Import-Module $ModuleName -UseWindowsPowerShell -Force
+                    & "Test-${ModuleName}PSEdition" | Should -Be 'Desktop'
+                }
+                else {
+                    { Import-Module $ModuleName -UseWindowsPowerShell -Force } | Should -Throw -ErrorId "InvalidOperationException"
+                }
+            }
+            finally {
+                [System.Management.Automation.Internal.InternalTestHooks]::SetTestHook("TestWindowsPowerShellVersionString", $null)
+            }
+        }
     }
 
     Context "Imports from absolute path" {