PRB: Unable to Locate URLMON.DLL on Windows NT 3.51

• The Microsoft Foundation Classes (MFC), included with: - Microsoft Visual C++, 32-bit Edition, versions 4.2, 5.0
• Internet Explorer (Programming), version 4.0

SYMPTOMS

When attempting to run an application built with Visual C++ 4.2 and 5.0, an error may be reported that the URLMON.DLL cannot be found. After this error, the application will abort.

This error will only occur if all of the following are true:

• The operating system is Windows NT 3.51.
• The executable is a debug build.
• The project is statically linked to MFC library.
• The project has enabled OLE functionality (directly or indirectly included afxole.h or afxdisp.h).

CAUSE

The URLMON.DLL is the DLL that supports the URL moniker. It is a part of the ActiveX SDK. The MFC library that ships with Visual C++ 4.2 and 5.0 takes advantage of this DLL for much of the Internet functionality added in Visual C++ 4.2. URLMON.DLL is not supported on Windows NT 3.51. Therefore, the DLL is not installed to your Windows NT 3.51 System32 directory.

MFC applications that target Windows NT 3.51 cannot use the URL moniker SDK functions. However, an application that meets all of the criteria listed in the Symptoms section of this article but does not use these functions will still attempt to load the DLL. Therefore, the run time error occurs.

RESOLUTION

To work around this problem, it is necessary to link the debug build of the application with the MFC DLL. The release build can continue to link statically to MFC. To link the debug build of the application to the MFC DLL, select the project settings dialog under the Build menu choice in Visual C++. Select the debug project in settings for list, and select "Use MFC in a Shared Dll(mfc42(d).dll)" under the general settings tab.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

Visual C++ 4.2 and 5.0 ship the Urlmon.dll as part of self-extracting installation files axdist.exe and wintdist.exe. This is covered in the \msdev\redist\redistrb.wri file.