INFO: Diagnosing "Error in loading DLL" with LoadLibrary

• Microsoft Visual Basic Professional and Enterprise Editions, 16-bit and 32-bit, for Windows, version 4.0
• Microsoft Visual Basic Professional and Enterprise Editions for Windows, version 5.0

SUMMARY

The error "Error in loading DLL" (code 48) occurs when you call a dynamic-link library (DLL) procedure and the file specified in the procedure's Declare statement cannot be loaded. You can use the Microsoft Windows API function LoadLibrary to find out more specific information about why a DLL fails to load.

MORE INFORMATION

The API function LoadLibrary loads a DLL and returns either a handle or an error code. If the return value is less than 32, it indicates one of the errors listed below. A return value greater than or equal to 32 indicates success and you should call the FreeLibrary function to unload the library.

LoadLibrary Error Codes

 0  System was out of memory, executable file was corrupt, or
    relocations were invalid.

 2  File was not found.

 3  Path was not found.

 5  Attempt was made to dynamically link to a task, or there was a
    sharing or network-protection error.

 6  Library required separate data segments for each task.

 8  There was insufficient memory to start the application.

 10 Windows version was incorrect.

 11 Executable file was invalid. Either it was not a Windows
    application or there was an error in the .EXE image.

 12 Application was designed for a different operating system.

 13 Application was designed for MS-DOS 4.0.

 14 Type of executable file was unknown.

 15 Attempt was made to load a real-mode application (developed for
    an earlier version of Windows).

 16 Attempt was made to load a second instance of an executable file
    containing multiple data segments that were not marked read-only.

 19 Attempt was made to load a compressed executable file. The file
    must be decompressed before it can be loaded.

 20 Dynamic-link library (DLL) file was invalid. One of the DLLs
    required to run this application was corrupt.

 21 Application requires Microsoft Windows 32-bit extensions. 

Steps to Create Example Program

1. Create a new Standard EXE Project in Visual Basic, Form1 is created by default.



2. Enter the following code into the general declarations section of Form1:
   

   
      #If Win32 Then
         Private Declare Function LoadLibraryEx Lib "Kernel32" Alias "LoadLibraryExA" _
            (ByVal lpLibFileName As String, _
            ByVal hFile As Long, _
            ByVal dwFlags As Long) As Integer
         Private Declare Sub FreeLibrary Lib "Kernel32" (ByVal hLibModule As Integer)
      #Else
         Private Declare Function LoadLibrary Lib "kernel" (ByVal f$) As Integer
         Private Declare Sub FreeLibrary Lib "Kernel" (ByVal h As Integer)
      #End If 




3. Enter the following code into the Form Click event handler:
   

   
         Private Sub Form_Click ()
            Dim hInst As Integer
            ' Enter the name of your DLL file inside the quotes below.
            ' The file WIN.COM is not a valid DLL and demonstrates an error.
            #If Win32 Then
               hInst = LoadLibraryEx("win.com", 0, 2)
               If hInst > 32 Then
                  MsgBox "LoadLibrary success"
                  FreeLibrary (hInst)
               Else
                  MsgBox "LoadLibrary error " + Format$(hInst)
               End If
            #Else
               hInst = LoadLibrary("win.com")
               If hInst > 32 Then
                  MsgBox "LoadLibrary success"
                  FreeLibrary (hInst)
               Else
                  MsgBox "LoadLibrary error " + Format$(hInst)
               End If
            #End If
         End Sub 




4. Press the F5 key to run the program. Then click Form1. The program displays the error code returned from LoadLibrary. Look up this error code in the list of errors above to find an explanation.

Additional query words:

Keywords : kb16bitonly kbVBp400 VB4WIN
Version : WINDOWS:4.0,5.0
Platform : WINDOWS
Issue type :