MSConfig.exe - Unable to Locate Component...This application failed to start because MFC42u.dll was not found. Re-installing the application may fix this problem.

I am using XP.

When I try to fix the problem by running sfs /scannow, I get the message:

"Files that are required for windows to run properly must be copied to the DLL cache...insert you windows XP professional service pack 3 cd now"

My machine came with XP preinstalled on D: drive.  I did make the HP Recovery Disc when I got the machine, but these disc don't work for this and I can't seem to redirect the scan to look on the "D" drive assuming that is the correct thing to do.

I have run windows one care and it says I have 150 errors it can't fix.  Before these problems started, it never reported more than one error it couldn't fix.






Santosh Y has the correct syntax to expand the file.  You already have the "expand" program on your system.

The files you see out in i386 with the underscore as the last character are compressed files (to save space). This kind of compression is not the same as when you tell XP to compress a file.  

It is sometimes useful to understand that you can uncompress any of those files out there is you need them if you come across one that is missing or suspicious sometime later.   Browse that folder and you will see a lot of compressed files where the last character is an underscore character.

Remember - sfc /scannow will not replace missing files and it will not replace a file that may have been overwritten by some other program, but you can always expand a fresh copy if you ever need to.

Just be careful to type the commands in perfectly to get it to work.

I have my XP Service Pack 3 installation CD copied out to my E drive in a folder called E:\xp_source and when I expanded my mfc42u.dl_ file I got a result like this:


C:\>expand e:\xp_source\i386\mfc42u.dl_ c:\windows\system32\mfc42u.dll

Microsoft (R) File Expansion Utility  Version 5.1.2600.0

Copyright (C) Microsoft Corp 1990-1999.  All rights reserved.

Expanding e:\xp_source\i386\mfc42u.dl_ to c:\windows\system32\mfc42u.dll .

e:\xp_source\i386\mfc42u.dl_: 378327 bytes expanded to 981760 bytes, 159% increase.


The new expanded file will not have the current date/time on it, so don't expect to see that - just verify the missing file is now present.

It would take some unnatural effort to actually delete one of the 3498 protected XP files like yours.  If you rename or just delete one of those files, Windows File Protection will quickly and silently replace it unless Windows File Protection is also broken, so you might want to figure out how your file became missing in the first place.  

If you manually delete or rename a monitored system file, you will see an event like this in the Event Viewer System log when Windows File Protection replaces it:

Event Type:    Information
Event Source:    Windows File Protection
Event Category:    None
Event ID:    64002
File replacement was attempted on the protected system file c:\windows\system32\mfc42u.dll. This file was restored to the original version to maintain system stability. The file version of the system file is

I would suspect some antivirus or antimalware application quarantied (effectively deleted) your file for you and that would be a problem.

Describe your current antivirus and anti malware situation:  McAfee, Symantec, Norton, Spybot, AVG, Avira!, MSE, Defender, ZoneAlarm, PC Tools, Comodo, etc.

Whatever you are using, you may want to follow up with these:

Download, install, update and do a full scan with these free malware detection programs:

Malwarebytes (MBAM):

SUPERAntiSpyware: (SAS):

They can be uninstalled later if desired.

When the scans run clean, then troubleshoot any remaining issues.

Do, or do not. There is no try.

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Question Info

Last updated November 10, 2019 Views 3,925 Applies to: