Christian Pfeiffer (ChrisTX) · Oct 30, 2026
@@ -15,6 +15,7 @@
 using Dbg = System.Management.Automation.Diagnostics;
 using System.Management.Automation.Help;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 
 namespace System.Management.Automation
 {
@@ -352,10 +353,12 @@ private HelpInfo GetHelpInfo(CommandInfo commandInfo, bool reportErrors, bool se
             {
                 if (isCmdlet)
                 {
+                    _originalHelpFiles.TryAdd(cmdletInfo, cmdletInfo.HelpFile);
                     cmdletInfo.HelpFile = helpFile;
                 }
                 else if (isFunction)
                 {
+                    _originalHelpFiles.TryAdd(functionInfo, functionInfo.HelpFile);
                     functionInfo.HelpFile = helpFile;
                 }
             }
@@ -491,6 +494,13 @@ private static string GetCmdletAssemblyPath(CmdletInfo cmdletInfo)
         /// </summary>
         private readonly Hashtable _helpFiles = new Hashtable();
 
+        /// <summary>
+        /// The original HelpFile property of the commands whose HelpFile was set to the file their help
+        /// was found in. A full path in HelpFile is loaded directly, so Reset() restores the original
+        /// values to search for the help again, e.g. in a new UI culture or after Update-Help.
+        /// </summary>
+        private readonly ConditionalWeakTable<CommandInfo, string> _originalHelpFiles = new ConditionalWeakTable<CommandInfo, string>();
+
         private string GetHelpFile(string helpFile, CmdletInfo cmdletInfo)
         {
             string helpFileToLoad = helpFile;
@@ -1304,6 +1314,20 @@ internal override void Reset()
             base.Reset();
 
             _helpFiles.Clear();
+
+            foreach (KeyValuePair<CommandInfo, string> entry in _originalHelpFiles)
+            {
+                if (entry.Key is CmdletInfo cmdletInfo)
+                {
+                    cmdletInfo.HelpFile = entry.Value;
+                }
+                else if (entry.Key is FunctionInfo functionInfo)
+                {
+                    functionInfo.HelpFile = entry.Value;
+                }
+            }
+
+            _originalHelpFiles.Clear();
         }
 
         #endregion

@@ -713,3 +713,44 @@ Describe 'InputTypes accurately describe pipelinable input' {
         $inputTypes | Should -Be "System.String"
     }
 }
+
+Describe "Get-Help searches for help again after its cache is reset" -Tags 'CI' {
+    BeforeAll {
+        $moduleName = 'HelpCacheResetTest'
+        $moduleBase = Join-Path $TestDrive $moduleName
+        foreach ($culture in 'en-US', 'de-DE') {
+            $null = New-Item -ItemType Directory -Path (Join-Path $moduleBase $culture) -Force
+            Set-Content -Path (Join-Path $moduleBase $culture "$moduleName-Help.xml") -Value @"
+<?xml version="1.0" encoding="utf-8"?>
+<helpItems schema="maml" xmlns="http://msh">
+  <command:command xmlns:maml="http://schemas.microsoft.com/maml/2004/10" xmlns:command="http://schemas.microsoft.com/maml/dev/command/2004/10" xmlns:dev="http://schemas.microsoft.com/maml/dev/2004/10">
+    <command:details>
+      <command:name>Get-HelpCacheResetTest</command:name>
+      <maml:description><maml:para>Help for $culture</maml:para></maml:description>
+    </command:details>
+  </command:command>
+</helpItems>
+"@
+        }
+
+        Set-Content -Path (Join-Path $moduleBase "$moduleName.psm1") -Value 'function Get-HelpCacheResetTest { }'
+        Import-Module (Join-Path $moduleBase "$moduleName.psm1")
+        $originalUICulture = [System.Globalization.CultureInfo]::CurrentUICulture
+    }
+
+    AfterAll {
+        [System.Globalization.CultureInfo]::CurrentUICulture = $originalUICulture
+        Remove-Module $moduleName -ErrorAction SilentlyContinue
+    }
+
+    It "Get-Help finds the help of the new UI culture after the help was found in another one" {
+        # Finding the help sets the HelpFile property of the command to the full path of the help file.
+        # A change of the UI culture resets the help cache, like Update-Help does, so the help has to be
+        # searched for again instead of loading that file.
+        [System.Globalization.CultureInfo]::CurrentUICulture = 'en-US'
+        (Get-Help Get-HelpCacheResetTest).Synopsis | Should -BeExactly 'Help for en-US'
+
+        [System.Globalization.CultureInfo]::CurrentUICulture = 'de-DE'
+        (Get-Help Get-HelpCacheResetTest).Synopsis | Should -BeExactly 'Help for de-DE'
+    }
+}