Replace MSVCRT.DLL on WinNT System

I am currently trying to manually replace the MSVCRT.DLL (Microsoft Visual C Runtime Library) on a Windows NT 4.0 SP6 machine. I have obtained a new version of the DLL since Xerces (http://xml.apache.org) doesn't run with the old/current version of the library.

I tried renaming the file while windows was running will all programs and extensions/processes killed and it was still being used by some program (possibly Windows itself was using it).

The next setup I tried was to create a batch file, which contained the copy function, and went into the system registry and entered it into \HKEY_LOCAL_MACHINE\Software\Microsoft\Current_Version\RunOnce. The batch file ran upon startup but still reported the file was in use.

I am not that savvy with NT 4.0 and have tried rebooting the machine to see if there is any way to get into a command-line only mode. With Win2K I know you can start in 'safe-mode: command prompt only' mode which you can use to do things like this. I cannot figure out how to get into the equivalent mode in NT4.0. I have read suggestions of using an MS-DOS boot disk but the file-system is NTFS and cannot be read by MS DOS disks. I have thought of using Knoppix to boot the system but then I remembered it only has read access to NTFS partitions.

Does anyone know how I can get into the system so I can replace this file.

Can you boot from the install CD? Otherwise, it's likely there's always going to be something using the C RTL, any sort of hard disk boot is likely going to have the file in use.

There's got to be a way to do it though. Someone in the Xerces community must have encountered it before, maybe some hardcore searching in their community/lists may bring something up?

Have been looking around and thinking of different things and found a couple of programs that allow mounting of NTFS drives under MS DOS. The first one I found, NTFSDOS, was free but is read only, not useful in my case. I did some more searching and found NTFSDOS Pro offering read/write access but costing US$299. I did some further searching and have found a copy of it that I am going to try out. I only need it once and can't justify spending US$299 for a one-time usage.

Hi koepke!

Here´s a WinAPI function that could be useful for that:
BOOL MoveFileEx(LPCTSTR lpExistingFileName, LPCTSTR pNewFileName, DWORD dwFlags);


Not sure if NT boots without the file though. I am not responsible for any harm it does to you, your computer or anybody´s g0ats

Choose Start>Programs>Command Prompt or Start>Programs>Accessories>Command Prompt and use the following commands (assuming the old DLL is located in C:\Temp):

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C:\Documents and Settings\Administrator>cd c:\winnt\system32

C:\WINNT\system32>rename msvcrt.dll msvcrt.old

C:\WINNT\system32>copy c:\temp\msvcrt.dll
Overwrite C:\WINNT\system32\msvcrt.dll? (Yes/No/All): y
1 file(s) copied.

C:\WINNT\system32>
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If you use the Command Prompt to rename the DLL NT/2000 lets you do it altough it simply creats a copy of the file because of the lock.

The lock gets moved on the copied file so it's now possible to restore the needed version of the DLL (still using the Command Prompt).

The above doesn't work, for the same reason as everything else, the msvcrt.dll is in use, at least on the serviced pack-applied version of NT I tried it on.

On Windows 2000, it's even in use if you boot to command prompt only.

So I thought I'd be smart, boot from a boot CD with NTFSPRO on it, and copy in the new version of the dll.

Bad idea! The next reboot came up with a Blue screen telling me that there was a checksum error with msvcrt.dll, it was possibly corrupt, blah blah blah. (again, this is on Win2K)

Oh, the misery...be careful folks...

umdesch4

You could try renaming the existing msvcrt dll and then copy the new one into the same directory, and reboot. Oops, I guess you tried that.

You could install a 2nd instance of NT4 to another folder (or better, another disk partition) and change the file whil booted into the 2nd instance.

There is a good chance you will cause other problems in other software if you change the dll to a non-standard version.