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After installing Process Explorer you get “Windows cannot find “C:\Windows\System32\taskmgr.exe”” when trying to open Task Manager

One of the first steps I do when installing a new computer is downloading process explorer and make it replace the default Windows Task Manager.

However, with my new computer not everything went so smooth and after setting Process Explorer to replace the Task Manager, it screwed something up. After that, every time I tried to load the task manager I received the error: “Windows cannot find “C:\Windows\System32\taskmgr.exe”:

Such things can drive me crazy!

Anyway, I researched a bit and found the problem, which just like any Windows problem sourced in the registry.

So if you have the same problem, follow the next steps to solve it:
Warning: modifying the registry incorrectly can cause serious problems that may require you to reinstall Windows. Handle with care!

  1. Open the registry (regedit is a great tool for that).
  2. Go to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe
  3. There you will find a string value named “Debugger”. This is the source of the problem and it’s probably filled with some unrecognizable string.
  4. If you want the default Task Manager back, set Debugger to a blank value.
  5. If you want to use Process Explorer as your task manager, set Debugger to the path to process explorer. For example, “c:\Utils\ProcessExplorer\procexp64.exe”.

That’s it.

All the best,

Comments (8) -

United States Lonnie Wall

I've found that the solution above doesn't work on 64-bit systems.  Process Explorer (procexp.exe) creates a separate 64-bit executable when it is launched on 64-bit systems.  When you replace the Windows Task Manager (taskmgr.exe) with Process Explorer, on 64-bit systems, the registry key HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\taskmgr.exe is set to <Process_Explorer_install_path>\procexp64.exe, but since procexp64.exe is removed after Process Explorer closes, the registry key value should be set to <Process_Explorer_install_path>\procexp.exe instead.  This resolves the issue once the change is made.


Very helpful.  Thanks!


Thank you, this worked. Process explorer is a great tool, but I wish he would also offer an installer version as well as better documentation.


Great help, thanks!


United States Bruiser Flint

Nice help, really appreciate it.

I have windows 7 64 bit and had this problem, your solution worked instantly.

Thank you so much, this has been bothering me for longer than I care to admit.

Thanks Microsoft for making things so tedious.


Canada viralvector

Thanks! You save my day.


Worked on Vista 64bit, thanks!


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