Public Function errHandling(ByVal sForm As String, _
  ByVal sFunction As String, _
  ByVal sErr As String)
 
  Dim f As Integer
 
  f = FreeFile
  Open errorLog For Append As #f
  Print #f, CStr(Now) & ";" & sForm & ";" & sFunction & ";" & sErr
  Close #f
  MsgBox "Es ist ein Fehler aufgetreten: " & vbNewLine & sErr, vbCritical
End Function

On Error goto errhandler
 
'.... CODE
'....
 
errhandler:
    errHandling CStr(Me.Name), "cmdRechnung_Click()", CStr(Err.Description) & _
      ":" & CStr(Err.Number)