Decoding API error message...

If you declare a DLL import with the SetLastError attribute then you can get the equivalent of VB classic's :

VB Code:

Err.LastDllError

with

VB Code:

System.Runtime.InteropServices.Marshal.GetLastWin32Error

..and like in VB classic you need to call the FormatMessage API call to get a description from this error:

VB Code:

Public Enum Format_Message_Flags
        FORMAT_MESSAGE_ALLOCATE_BUFFER = &H100
        FORMAT_MESSAGE_IGNORE_INSERTS = &H200
        FORMAT_MESSAGE_FROM_STRING = &H400
        FORMAT_MESSAGE_FROM_HMODULE = &H800
        FORMAT_MESSAGE_FROM_SYSTEM = &H1000
        FORMAT_MESSAGE_ARGUMENT_ARRAY = &H2000
    End Enum
 
    Private Const MAX_MESSAGE_LENGTH = 512
 
    <DllImport("kernel32.dll", EntryPoint:="FormatMessageA", _
     CharSet:=CharSet.Ansi, _
     ExactSpelling:=True, _
     CallingConvention:=CallingConvention.StdCall)> _
    Private Function FormatMessage(ByVal dwFlags As Format_Message_Flags, ByVal lpSource As Int32, ByVal dwMessageId As Int32, ByVal dwLanguageId As Int32, ByVal lpBuffer As String, ByVal nSize As Int32, ByVal Arguments As Int32) As Int32
 
    End Function
 
   Public Function GetAPIErrorMessageDescription(ByVal ApiErrNumber As Int32) As String
 
        Dim sError As New StringBuilder(MAX_MESSAGE_LENGTH)
        Dim lErrorMessageLength As Int32
 
        lErrorMessageLength = FormatMessage(Format_Message_Flags.FORMAT_MESSAGE_FROM_SYSTEM, 0, ApiErrNumber, 0, sError, sError.Capacity, &H0)
        If lErrorMessageLength > 0 Then
            GetAPIErrorMessageDescription = sError.ToString
        End If
 
 
    End Function

Hope this helps,
Duncan