A significant regression in Microsoft's optional Windows 11 preview update KB5067036, released on October 28, 2025, is causing Task Manager processes to remain active even after users close the application window, creating multiple invisible instances that consume system resources and potentially impact performance. This baffling bug represents a step backward in Microsoft's process management system, where the very tool designed to monitor and control system processes is now contributing to the problem it's meant to solve.

The Technical Breakdown of the Task Manager Bug

The KB5067036 preview update, which was intended to deliver various improvements and fixes to Windows 11 users, instead introduced a critical flaw in how the Task Manager application handles process termination. When users open Task Manager through any method—whether by pressing Ctrl+Shift+Esc, right-clicking the taskbar, or searching for it in the Start menu—the application appears to function normally. However, when users close the Task Manager window using the standard X button in the upper-right corner or through the File > Exit menu option, the visual interface disappears while the underlying taskmgr.exe process continues running in the background.

Multiple users testing the preview build have reported that each subsequent opening and closing of Task Manager creates additional orphaned processes, with some systems accumulating dozens of invisible taskmgr.exe instances over time. These processes typically consume between 15-25 MB of RAM each, which may seem minimal individually but can collectively impact system performance, especially on devices with limited memory resources.

How to Identify and Monitor the Issue

Users can verify whether they're affected by this bug through several methods. The most straightforward approach is to open Task Manager itself and check the Processes tab—if multiple taskmgr.exe entries appear even when only one Task Manager window is visible, the system is experiencing the bug. Alternatively, users can employ PowerShell or Command Prompt with the command tasklist | findstr taskmgr to list all running Task Manager instances.

For those preferring graphical interfaces, third-party process monitoring tools like Process Explorer from Microsoft's Sysinternals suite can provide a more detailed view of all running processes, including hidden instances of taskmgr.exe. The cumulative effect becomes particularly noticeable when users monitor their system's memory usage over time, observing gradual increases that correspond with Task Manager usage sessions.

Impact on System Performance and User Experience

While individual orphaned Task Manager processes consume relatively modest resources, the cumulative effect can become significant. On systems where users frequently access Task Manager for system monitoring or troubleshooting, the buildup of multiple instances can consume hundreds of megabytes of RAM that would otherwise be available for active applications and system operations.

The performance impact extends beyond mere memory consumption. Each running process requires CPU cycles for scheduling and maintenance, creates entries in system tables, and occupies handles and other system resources. For users running resource-intensive applications like video editing software, development environments, or virtual machines, these orphaned processes can contribute to system slowdowns and reduced responsiveness.

Perhaps more concerning is the psychological impact on users who rely on Task Manager as a troubleshooting tool. When the very application meant to help identify and resolve system issues becomes part of the problem, it undermines user confidence in the operating system's stability and reliability.

Temporary Workarounds and Manual Solutions

Until Microsoft releases an official fix, affected users have several options for managing the issue. The most immediate solution is to manually terminate orphaned Task Manager processes through the existing Task Manager interface or command-line tools:

  • Open Task Manager (which will create another instance)
  • Navigate to the Details tab
  • Locate all taskmgr.exe entries
  • Select each orphaned instance and click "End Task"
  • Be careful to leave one instance running if you need to continue using Task Manager

For command-line enthusiasts, the process can be automated with a batch file or PowerShell script that identifies and terminates excess Task Manager instances while preserving at least one active process for system monitoring.

Some users have reported success with creating custom shortcuts that include command-line parameters to force proper process termination, though the effectiveness of these workarounds varies depending on system configuration and usage patterns.

The Broader Context of Windows Preview Build Issues

This Task Manager regression isn't an isolated incident in Microsoft's Windows Insider program. Preview builds inherently carry higher risks as they represent unfinished software undergoing testing and refinement. However, the nature of this particular bug—affecting such a fundamental system tool—highlights the challenges Microsoft faces in maintaining backward compatibility while implementing new features and optimizations.

Recent Windows 11 updates have introduced various issues, from minor interface glitches to more significant functionality problems. The KB5067036 update specifically was intended to address several known issues from previous builds while introducing new features and improvements. The fact that it instead created a new problem with one of Windows' most essential utilities demonstrates the complexity of modern operating system development.

Microsoft's Response and Expected Timeline for Fixes

Microsoft typically addresses critical issues in preview builds through subsequent updates rather than pulling the problematic build entirely. The development cycle for Windows Insider builds means that fixes for issues identified in optional preview updates like KB5067036 usually appear in the next scheduled update, which could be days or weeks away depending on the severity of the problem and the complexity of the solution.

Users participating in the Windows Insider program should monitor official channels, including the Windows Insider Blog and release notes for new builds, for announcements regarding fixes for the Task Manager orphaned process issue. Microsoft's track record suggests they prioritize fixes for system-critical components like Task Manager, so a resolution will likely arrive in an upcoming preview build before the changes reach the general public through stable channel updates.

Best Practices for Windows Insider Participants

For users experiencing this issue, several practices can help minimize impact while waiting for an official fix:

  • Limit unnecessary Task Manager usage
  • Regularly check for and manually terminate orphaned processes
  • Consider using alternative system monitoring tools temporarily
  • Monitor system resource usage to identify when cleanup is needed
  • Report the issue through official Feedback Hub channels to help Microsoft prioritize the fix

Participants in the Windows Insider program should remember that preview builds represent work in progress and may contain unexpected issues. Maintaining regular backups and having rollback plans ensures that system stability isn't compromised while testing new features and improvements.

Historical Context of Task Manager Issues

This isn't the first time Task Manager has experienced significant bugs in Windows releases. Previous versions of Windows have encountered various Task Manager-related issues, including:

  • Display refresh problems where process lists wouldn't update properly
  • Performance counter inaccuracies in earlier Windows 10 builds
  • Interface scaling issues on high-DPI displays
  • Security vulnerabilities related to process manipulation

What makes the current issue notable is its persistence aspect—rather than temporary display or functional problems, this bug creates lasting system impact through resource consumption that continues even after the user believes they've closed the application.

The Technical Challenge of Process Lifecycle Management

The orphaned Task Manager process issue highlights the complexities of modern application lifecycle management in Windows. When users close an application window, they reasonably expect the entire process to terminate cleanly. However, the reality involves multiple components working together:

  • The user interface thread handling window messages
  • Background threads performing monitoring and data collection
  • Inter-process communication with other system components
  • Hook procedures for monitoring system events

A failure in any of these areas can prevent proper cleanup, leaving processes running without their associated user interfaces. In Task Manager's case, the application's deep integration with Windows system monitoring facilities makes it particularly susceptible to such issues when underlying APIs or system behaviors change.

Looking Forward: Prevention and Quality Assurance

This incident raises questions about Microsoft's testing procedures for fundamental system components. While preview builds exist specifically to identify such issues before they reach all users, the fact that a regression affecting such a critical tool made it through initial testing suggests potential gaps in automated testing coverage or scenario validation.

Moving forward, users can expect Microsoft to enhance their testing protocols for Task Manager and similar system utilities, potentially including more comprehensive process lifecycle validation and resource cleanup verification. The company's increased focus on artificial intelligence and machine learning in their development processes may also help identify such regressions earlier in the development cycle.

For now, Windows Insider participants serving as Microsoft's first line of defense against such issues play a crucial role in identifying, reporting, and working around problems until official fixes arrive. Their feedback and testing continue to be essential in shaping the stable, reliable Windows experience that eventually reaches all users.