FIX: Can Not Attach Process to Debugger from NT Task Manager

ID: Q167798

The information in this article applies to:

Microsoft Visual C++, 32-bit Editions, version 5.0

SYMPTOMS

After installing Visual C++ version 5.0, you may not be able to attach an active process from Windows NT Task Manager. A message box titled "Unable to Attach Debugger" with the following error message appears:

The operation could not be completed. The system cannot find the file
specified.

CAUSE

This happens because the registry entry in HKEY_LOCAL_MACHINE\SOFTWARE\ Microsoft\Windows NT\CurrentVersion\AeDebug has a space in the path to MSDEV.EXE. By default, the installed path to MSDEV.EXE is C:\Program Files\DevStudio\SharedIDE\BIN\.

RESOLUTION

The resolution is to change the entry in the AeDebug registry key to:


   "<install drive>\Program Files\DevStudio\SharedIDE\BIN\msdev.exe" -p %id - e %id

The quotation marks around the executable path and name are necessary in order to correct this problem.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This problem was corrected in Visual C++ version 6.0 for Windows.

MORE INFORMATION

The registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\ CurrentVersion\AeDebug is used to attach the Visual C++ debugger to an active process by launching MSDEV.EXE. It is also used by Just-In-Time (JIT) debugging for the same purpose.

After you install Visual C++, the above registry key will have the following value:


<drive>\Program Files\DevStudio\SharedIDE\BIN\msdev.exe -p %id -e %id

where <drive> is the drive letter where Visual C++ is installed.

JIT debugging works fine with the value above.

The following are two ways you can attach an active process to the Visual C++ debugger:

In Developer Studio, from the Build menu, Start Debug allows you to Attach to Process where you select an active process from the list provided.

In Windows NT, open the Task Manager, right-click an active process, and select Debug in the pop-up window. This attaches the Visual C++ debugger to the selected active process.
For additional information about this method , please see the following article in the Microsoft Knowledge Base:

Q120707 How to Debug an Active Process in 32-bit Visual C++

The first method works without having to incorporate the fix described in this article because Visual C++ is already running.

Steps to Reproduce Behavior

Start Windows NT Task Manager by pressing CTRL+ALT+DEL, and then select Task Manager from the system dialog box.

Click the Processes tab, then right-click the process you want to attach to the debugger, and select Debug. If the fix described above is not in place, you will not be able to debug the process and you will receive the error message described in the SYMPTOMS section.

As mentioned earlier, Just-in-time debugging and attaching to a process from Developer Studio works without using the fix described in this article.

WARNING: Toggling the Just-in-time debugging check box in the Developer Studio Options, Debug Menu tab rewrites the AeDebug registry key back to its original value.

Keywords : kbtool kbDebug kbide kbVC500bug kbVC600fix
Version : winnt:5.0
Platform : winnt
Issue type : kbbug