Microsoft KB Archive/163556

= "Unable to Register Mfc40.dll" Error During MS Office Install =

Article ID: 163556

Article Last Modified on 8/17/2005

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APPLIES TO


 * Microsoft Office 97 Standard Edition
 * Microsoft Office 95 Standard Edition
 * Microsoft Office 95a
 * Microsoft Office 95b

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This article was previously published under Q163556



SYMPTOMS
When you run the Microsoft Office Setup program, you receive the following error message:

Unable to register Mfc40.dll



CAUSE
This error message appears because the versions of certain .dll files that exist in the Windows\System or Winnt\System32 folder are the wrong versions.



RESOLUTION
To resolve this problem, use the following procedure.

Locate and Rename Files
To find and rename the files, follow these steps:  Use Microsoft Windows Explorer to locate the Mfc40.dll file.

By default, this file is in the Windows\System folder (under Microsoft Windows 95) or in the Winnt\System32 folder (under Microsoft Windows NT 4.0).

NOTE: If you are unable to find this file, click Options on the View Menu in Windows Explorer. Click the View tab, click Show All and click OK.

If you cannot find the file in either of the folder locations, use the Find File feature to locate it. To do this, follow these steps:  Click Start, point to Find, and then click Files Or Folders. In the Find dialog box, click the Name & Location tab. In the Named box, type the file name.

In this case, the file name is Mfc40.dll. In the Look In box, type or select drive C. Click to select the Include Subfolders check box.</li> Click Find Now.</li> All copies of the file that exist on your system are listed in the lower portion of the Find dialog.</li> Make a note of the location of all copies of the file.</li></ol> </li> After you locate the Mfc40.dll file, rename it. To rename the file, right-click the file name, and click Rename on the shortcut menu. Type Mfc40.bak, and then press ENTER to rename the file. Rename all copies of the Mfc40.dll file.

NOTE: If you receive an error message that indicates that you cannot rename the name, go to the "What to Do If the File Is in Use and Cannot Be Renamed" section.</li> Repeat step 1 to locate and rename the Msvcrt40.dll file to Msvcrt40.bak. Rename all copies of the Msvcrt40.dll file.</li> Run the Microsoft Office Setup program. If the Setup program runs in maintenance mode, click Reinstall. Otherwise, choose the type of installation that you want to perform.</li></ol>

What to Do If the File Is in Use and Cannot Be Renamed
In some cases, Windows 95 or Windows NT 4.0 may be using the Msvcrt40.dll or Mfc40.dll file. If this is the case, do the following to replace the file:
 * 1) Restart your computer, but press and hold the SHIFT key to disable all startup programs.
 * 2) Close all tasks except Systray and Explorer. To do this, press CTRL+ALT+DEL to display the Task List. In the Close Program dialog box, click the task you want to close, and then click End Task.
 * 3) Use the steps in the "Locate and Rename Files" section to rename the existing Msvcrt40.dll file to Msvcrt40.bak. Then rename the existing Mfc40.dll file to Mfc40.bak.
 * 4) When you restart your computer, you may receive an error message that indicates that Msvcrt40.dll or Mfc40.dll cannot be found. If this occurs, click OK.
 * 5) Run the Microsoft Office Setup program. The Microsoft Office Setup program installs both the Mfc40.dll and Msvcrt40.dll files.

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MORE INFORMATION
The error message listed in the "Symptoms" section may appear when certain .dll files are not the version that the Setup program expects to find. The files may be the "wrong" version because of hardware or BIOS (basic input/output system) conflicts or Microsoft Windows 95 or Windows NT registry problems.

Some programs install different versions of the Mfc40.dll and the Msvcrt40.dll files from the versions the Microsoft Office Setup program installs. If one of the files is the wrong version, the Microsoft Office Setup program may fail to complete successfully.

Both Microsoft Office 7.0 and Microsoft Office 97 install the following versions of the Mfc40.dll and Msvcrt40.dll files:

<pre class="fixed_text">  Mfc40.dll       Size: 924,432 bytes   Version: 4.1.6139 Msvcrt40.dll   Size: 326,656 bytes   Version: 4.10.6038

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