FIX: For..Each Loop in ActiveX Component Causes Errors

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 5.0
• Microsoft Visual Studio versions 97sp2, 97sp3

SYMPTOMS

When using an ActiveX DLL created in Visual Basic, you may receive one of the following errors if the ActiveX component contains a For..Each loop that iterates through a Visual Basic collection:

Run-time error '48':
Error in loading DLL

-or-

Run-time error '-2147319765 (8002802b)':
Automation Error

CAUSE

This problem typically occurs after calling the DLL at least twice. The first call into the DLL does not execute code that uses a For..Each loop but the second call does. The error occurs during the second call. See the "Steps to Reproduce Behavior" section below for more information.

RESOLUTION

• Use a For..Next loop in place of the For..Each loop.
  
  -or-



• Create your own collection class, an example of which can be found in the Visual Basic Books Online. Refer to the topic "Creating Your Own Collection Classes."
  
  -or-



• If your DLL is running in a multithreaded environment like Internet Information Server (IIS) or Microsoft Transaction Server (MTS), please see the following article here in the Microsoft Knowledge Base:
  
  

  Q186273 BUG: AV Running VB-Built Component in Multi-Threaded Environment

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem has been corrected in Microsoft Visual Basic 6.0.

NOTE: If your DLL is running in a multi-threaded environment, you must still complete the steps provided in the following article in the Microsoft Knowledge Base:

Q186273 BUG: AV Running VB-Built Component in Multi-Threaded Environment

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a new ActiveX DLL project in Visual Basic.



2. Click Project1 Properties from the Project menu and set the Project Name to "AutoErr1."



3. Copy the following code to the Class1 module:
   

   
         Public Sub Method1()
            Dim col As New Collection
            Dim obj As Object
            For Each obj In col
            Next obj
         End Sub
    




4. Click "Make AutoErr1.dll" from the File menu to create the DLL file.



5. Quit Visual Basic. You may optionally save the project files.



6. Start Microsoft Excel 97 and create a new workbook. Press the ALT+F11 keys to start the Visual Basic editor.



7. Click Module from the Insert menu to add a standard module. Add the following code to the new module:
   

   
         Private Sub Test48()
            ' First call into dll
            Dim o as Object
            Set o = CreateObject("AutoErr1.Class1")
            Set o = Nothing
            ' Second call into dll
            Set o = CreateObject("AutoErr1.Class1")
            o.Method1 ' calls method that uses For..Each loop
            set o = Nothing
         End Sub
    




8. Press the F8 key to step through the Sub's code and note that the following error occurs when calling Method1:
   

   Run-time error '48':
   Error in loading DLL

1. Follow steps 1 through 5 above to create the AutoErr1.dll.



2. Start a new Standard EXE project in Visual Basic. Form1 is created by default.



3. Place 2 CommandButtons (Command1 and Command2) on Form1.



4. Copy the following code to the Form1 module:
   

   
         Private Sub Command1_Click()
            ' First call into dll
            Dim o As Object
            Set o = CreateObject("AutoErr1.Class1")
            Set o = Nothing
         End Sub
   
         Private Sub Command2_Click()
            ' Second call into dll
            Dim o As Object
            Set o = CreateObject("AutoErr1.Class1")
            o.Method1
            Set o = Nothing
         End Sub
    




5. Press the CTRL+F5 keys to run the project.



6. Click Command1.



7. Click Command2. Note that the following error may occur when calling Method1:
   

   Runtime-error '-2147319765 (8002802b)':
   Automation Error

REFERENCES

For additional information, please see the following article in the Microsoft Knowledge Base:

Q178777 : PRB: ASP Returns "Error in Loading DLL" with VB Component

Additional query words: element not found

Keywords : kberrmsg kbVBp500 kbVBp500bug kbVBp600fix kbVS97sp2bug kbVS97sp3bug kbGrpVB VBKBAX
Version : WINDOWS:5.0,97sp2,97sp3
Platform : WINDOWS
Issue type : kbbug