Q272490: BUG: Error "Cannot Save an Uninitialized Class" on VB Component

Article: Q272490
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.0,5.0,6.0
Operating System(s): 
Keyword(s): kberrmsg kbASP kbCOMPlus kbIE400 kbMTS kbVBp600 kbie500 kbDSupport
Last Modified: 08-MAY-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 
- Microsoft Visual Basic Professional Edition for Windows, version 6.0 
- Microsoft Internet Information Server versions 4.0, 5.0 
- Microsoft Active Server Pages, version 1.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

When you create a Visual Basic ActiveX dynamic-link library (DLL) from Active
Server Pages (ASP) or from another Microsoft Transaction Server component with
CreateInstance and call a method on it that writes to a PropertyBag object, you
may receive the following error message when you call the WriteProperty method
on the PropertyBag:

  Error Type:
  SomeComponent (0x800A02E0)
  Cannot save an uninitialized class. You must use the global InitProperties
  method to initialize the class, or load the class from a PropertyBag before
  trying to save it.

This problem does not occur when you create the component from Visual Basic with
the New keyword.

CAUSE
=====

This problem occurs because the IPersistStream::InitNew method is not called on
the component that is saved. When the component is created from Visual Basic
with New, the Visual Basic runtime calls InitNew for you.

RESOLUTION
==========

To work around this problem, create the component through a factory component in
Visual Basic so that Visual Basic creates the component and calls InitNew on the
IPersistStreamInit interface.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Create a new Visual Basic ActiveX DLL. Rename the project "MyBag" and the
  class "CBag".

2. Set the persistable property of CBag to "1 persistable".

3. Add the following code and compile:

  Private n As Long

  Private Sub Class_InitProperties()
      n = 12
  End Sub

  Private Sub Class_ReadProperties(PropBag As PropertyBag)
      n = PropBag.ReadProperty("n")
  End Sub

  Private Sub Class_WriteProperties(PropBag As PropertyBag)
      PropBag.WriteProperty "n", n
  End Sub

  Public Function Serialize() As Byte()

     Dim pbgState As PropertyBag
     
     Set pbgState = New PropertyBag
     
     pbgState.WriteProperty "TestSerialize", Me
     
     Serialize = pbgState.Contents
     
     Set pbgState = Nothing
    
  End Function

4. Create an ASP page named Mybag.asp, and paste the following code:

  <%
  	set bag = Server.CreateObject("Bag.CBag")
  	bag.Serialize
  	response.write "Done" 
  %>

5. In your browser, open the page. You receive the above-mentioned error.

Workaround
----------

1. Add another class to the project named CBagFactory.

2. Add a function called CreateBag as follows:

  Public Function CreateBag() As CBag
      Set CreateBag = New CBag
  End Function

3. Recompile the DLL.

4. Replace the ASP code with the following code:

  <%
  	set fac = Server.CreateObject("Bag.CBagFactory")
  	set bag = fac.CreateBag
  	bag.Serialize
  	response.write "Done" 
  %>

5. In your browser, run the ASP page. You do not receive the error message.

REFERENCES
==========

For additional information, click the article number below to view the article
in the Microsoft Knowledge Base:

  Q241896 PRB: Threading Issues with Visual Basic 6.0 ActiveX Components

Additional query words: 0x800A02E0

======================================================================
Keywords          : kberrmsg kbASP kbCOMPlus kbIE400 kbMTS kbVBp600 kbie500 kbDSupport 
Technology        : kbVBSearch kbiisSearch kbAudDeveloper kbASPsearch kbZNotKeyword6 kbiis500 kbiis400 kbZNotKeyword2 kbVB600Search kbVBA600 kbVB600
Version           : :4.0,5.0,6.0
Issue type        : kbbug
Solution Type     : kbnofix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.