KB5072911: Explorer, the Start menu not working

Hi,

I'm writing to follow up with the issue. The fact that it's affecting such a wide range of OS versions simultaneously, from stable Windows 10 (19045) to the latest Windows 11 Insider builds (26200), is the single most important clue.

Because Microsoft updates are version-specific (a Windows 10 update does not apply to Windows 11 Canary), we can definitively rule out a "bad Microsoft update" (like KB5072911) as the root cause. This behavior confirms the culprit is a shared third-party software, security agent, or shell extension installed across your entire fleet that is incompatible with the Windows Shell.

To fix this, we need to stop guessing and identify the exact DLL file causing explorer.exe to crash.

If you can provide the Faulting module name from that Event ID 1000, I can give you the exact uninstall target to resolve this fleet-wide.

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer then. Should you have more questions, feel free to leave a message. Have a nice day!

VP

It seems that you are experiencing issues with the Start menu and Windows Explorer across multiple versions of Windows, and the recent update (KB5072911) did not resolve these problems. Here are some troubleshooting steps you can consider:

1. Check for Updates: Ensure that all systems are running the latest Feature and Cumulative Monthly updates. Sometimes, subsequent updates may fix lingering issues.
2. Check Start Menu Installation: Use PowerShell to verify if the Start menu package is installed. Run the following command in a non-elevated PowerShell prompt:

      Get-AppxPackage -Name Microsoft.Windows.StartMenuExperienceHost
   

   If there is no response, try checking for all users:

      Get-AppxPackage *StartMenu* -AllUsers
   

3. Register the Start Menu: If the package exists but is not registered for the user, you can register it using:

      Add-AppxPackage -Path "C:\Windows\SystemApps\Microsoft.Windows.StartMenuExperienceHost_cw5n1h2txyewy\AppxManifest.xml" -Register -DisableDevelopmentMode
   

   Make sure to run this command in a non-elevated prompt.
4. Check for Application Crashes: Use the following command to check if the Start menu process is running:

      get-Process StartMenuExperienceHost -IncludeUserName
   

   If it is not running, consider booting into safe mode to troubleshoot further.
5. Event Logs: Review the Application event log for Event IDs 1000 and 1001 related to StartMenuExperienceHost.exe to identify any crashes or issues.
6. Group Policies: Check if there are any Group Policy settings that might restrict access to the Start menu or related components.

If these steps do not resolve the issues, you may need to consider further investigation into the specific configurations or policies applied to the affected systems.

References:

• Start menu troubleshooting guidance
• Issues with deployment or installation
• Issues with application crashes

Hi Tom Crimmins,

The issue spans disjointed operating system generations, from legacy Windows 10 22H2 (Build 19045) to the bleeding-edge Windows 11 Canary (Build 26200). Because these OS versions rely on fundamentally different codebases for their shell infrastructure, this is almost certainly not caused by a specific Windows Update (like the KB you mentioned). It is highly likely caused by a shared Third-Party Shell Extension, a Security Agent update, or a Driver present on all machines that is injecting itself into the explorer.exe process and crashing it.

The "Blinking tool bar" indicates explorer.exe is entering a crash loop (starting, crashing, restarting), while "No Start Menu" indicates the UWP Shell infrastructure (ShellExperienceHost) is blocked or hung.

Here is the troubleshooting path to identify and kill the culprit:

Step 1: Identify the "Faulting Module" (The Smoking Gun)

We need to know exactly what DLL is crashing Explorer. You cannot fix this by guessing.

On an affected machine, press CTRL + SHIFT + ESC to open Task Manager. Click Run new task, type eventvwr, and hit Enter. Navigate to Windows Logs > Application. Filter the log for Error level and Event ID 1000 (Application Error).

Find the most recent crash for explorer.exe. Look at the Faulting module name:

If it is a Microsoft DLL (e.g., ucrtbase.dll, windows.ui.xaml.dll): The shell database is corrupted (Proceed to Step 3).

If it is a Non-Microsoft DLL (e.g., barcocalendar.dll, ctxmenu.dll, or an Antivirus DLL): That is your root cause. Uninstall or update that specific software immediately.

Step 2: The "Barco ClickShare" Check (High Probability)

I mention this specifically because "Blinking Taskbar" + "Unresponsive Start Menu" is the exact signature of a known conflict with the Barco ClickShare app's calendar integration. If your organization uses these devices:

Open Task Manager, find the ClickShare process, and End Task.

If the blinking stops immediately, the fix is to open the ClickShare App > Settings > Disable "Calendar Integration".

Step 3: Re-register the Shell Infrastructure (PowerShell)

If Step 1 shows a Microsoft module crash, the AppX database for the Start Menu is corrupted. You must force Windows to rebuild it.

Open Task Manager > Run new task. Type powershell. Important: Check the box "Create this task with administrative privileges". Run the following command to re-register the Experience Host (Fixes Start Menu):

Get-AppxPackage -AllUsers Microsoft.Windows.ShellExperienceHost | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

(For the Windows 10 "Blinking" machines) Run this broader command to re-register all inbox apps:

Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

(Note: Ignore the red text errors that appear during this process; they are normal for running processes).

Step 4: Check ASR Rules (Defender)

If you use Microsoft Defender for Endpoint, a bad "Attack Surface Reduction" (ASR) rule update can block shell processes. Check your Defender portal or Event Viewer (Applications and Services > Microsoft > Windows > Windows Defender > Operational) for Event ID 1121 (ASR Block). If found, set the offending rule to "Audit Mode."

I hope you've found something useful here. If it helps you get more insight into the issue, it's appreciated to accept the answer . Should you have more questions, feel free to leave a message. Have a nice day!

VPHAN