Error Message: Error 745: An Essential File Is Missing

ID: Q174579

The information in this article applies to:
IMPORTANT: This article contains information about editing the registry. Before you edit the registry, you should first make a backup copy of the registry files (System.dat and User.dat). Both are hidden files in the Windows folder.

SYMPTOMS

When you attempt to connect to a remote computer using Dial-Up Networking, you may receive the following error message:

Error 745: An essential file is missing.
Re-install Dial-Up Networking.


CAUSE

This error message can occur when a Dial-Up Networking dynamic-link library (DLL) file is missing or damaged.


RESOLUTION

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows 95/98. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

NOTE: For information about how to edit the registry, view the Changing Keys And Values online Help topic in Registry Editor (Regedit.exe). Note that you should make a backup copy of the registry files (System.dat and User.dat) before you edit the registry.

To resolve this issue, remove and reinstall Dial-Up Networking. To do this, follow these steps:

  1. Click Start, point to Settings, and then click Control Panel.


  2. Double-click Add/Remove Programs.


  3. Click the Windows Setup tab, click Communications, and then click Details.


  4. Click the Dial-Up Networking check box to clear it, click OK, and then click OK again.


  5. Click Start, click Shut Down, click Restart Your Computer, and then click Yes.


  6. Click Start, point to Programs, and then click Windows Explorer.


  7. If it exists, rename the Rasapi32.dll file located in the Windows\System folder.

    For information about how to rename a file, click Start, click Help, click the Index tab, type "renaming" (without quotation marks), and then double-click the "Renaming files" topic.


  8. Extract a new copy of the Rasapi32.dll file from your original Windows 95/98 CD-ROM or floppy disks into the Windows\System folder. To do this, use the appropriate method:

    Extracting Rasapi32.dll from the Windows 95 CD-ROM:

    1. Click Start, point to Programs, and then click MS-DOS Prompt.


    2. Type cd\, and then press ENTER.


    3. Insert the Windows 95 CD-ROM into the CD-ROM drive, and then close the Windows 95 screen if it appears.


    4. Type the following line at the command prompt, and then press ENTER

      extract /a <drive>:\win95\win95_02.cab rasapi32.dll /l c:\<windows>\system

      where <drive> is the drive letter assigned to your CD-ROM drive, and where <windows> is the name of the folder in which Windows is installed.


    5. Type exit, and then press ENTER to return to windows.


    Extracting Rasapi32.dll from the Windows 95 Floppy Disks:

    1. Click Start, point to Programs, and then click MS-DOS Prompt.


    2. Type cd\, and then press ENTER.


    3. Insert disk 10 of the Windows 95 disks into the floppy disk drive.


    4. Type the following line at the command prompt, and then press ENTER

      extract /a <drive>:\Win95_10.cab rasapi32.dll /l c:\<windows>\system

      where <drive> is the drive letter assigned to the floppy disk drive the Windows 95 floppy disk is located in, and where <windows> is the name of the folder in which Windows is installed.


    5. Type exit, and then press ENTER to return to windows.


    Extracting Rasapi32.dll in Windows 98:

    Extract a new copy of the Rasapi32.dll file from your original Windows 98 CD-ROM into the Windows\System folder using the System File Checker tool. To start the System File Checker tool, click Start, click Run, type sfc.exe in the Open box, and then click OK.

    For more information about using the Extract tool, click the Start button, point to Programs, click MS-DOS prompt, type "extract" (without quotation marks), and then press ENTER. For more information about using the Extract tool or System File Checker, see the following article in the Microsoft Knowledge Base:
    ARTICLE-ID: Q129605
    TITLE : How to Extract Original Compressed Windows Files


  9. Use Registry Editor to delete the SMM_Files key under the following registry key:


    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RemoteAccess\Authentication


  10. Click Start, click Settings, and then click Control Panel.


  11. Double-click Add/Remove Programs.


  12. Click the Windows Setup tab, click Communications, and then click Details.


  13. Click the Dial-Up Networking check box to select it, click OK, and then click OK again.


  14. When you are prompted to restart your computer, click Yes.


  15. If you had previously installed Dial-Up Scripting in Windows 95, rename the Smmscrpt.dll file in the Windows\System folder, and then reinstall Dial-Up Scripting.

    For information about installing Dial-Up Scripting, please see the following article in the Microsoft Knowledge Base:
    ARTICLE-ID: Q153038
    TITLE : How to Automate Dial-Up Networking Connections



MORE INFORMATION

To determine the DLL file used by Dial-Up Networking, view the Path value under the following registry key:


HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RemoteAccess\Authentication\SMM_Files\PPP

The default value is "Rasapi32.dll." If Dial-Up Scripting is installed in Windows 95, this value may be "Smmscrpt.dll."



CompuServe's WOW! software, which is included with Windows 95 OEM Service Release 2 (OSR2), changes the Path value to "Smmcctb.dll" and adds "CISPPP: PPP connection using CompuServenetworks" to the available server types in the Dial-Up Networking connection properties.

The CompuServe WOW! software should no longer be necessary because CompuServe discontinued the WOW! service as of January 31, 1997.

Additional query words: msnetwork msn 


Keywords          : kberrmsg dun win95 win98 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbprb

Last Reviewed: January 30, 1999