Microsoft KB Archive/223245

= ACC2000: Error When You Close a Form That Instantiates a Class Module =

Article ID: 223245

Article Last Modified on 6/24/2004

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APPLIES TO


 * Microsoft Access 2000 Standard Edition

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This article was previously published under Q223245





Advanced: Requires expert coding, interoperability, and multiuser skills.

This article applies to a Microsoft Access database (.mdb) and to a Microsoft Access project (.adp).



SYMPTOMS
When you try to close a form that contains code that instantiates a class object, Microsoft Access may stop responding (hang), or you may receive the following error message:

This program has performed an illegal operation and will be shut down.

If the problem persists, contact the program vendor.

When you click Details (on Microsoft Windows Millennium Edition, press ALT+D), you receive the following message:

MSACCESS caused an invalid page fault in MSACCESS.EXE at 015f:300581e7.

NOTE: The actual memory address may vary.



CAUSE
This problem occurs when both of the following are true:  You use WithEvents in the Class module to track the form's events.  In the Close or Unload event of the form, you destroy an object with the following statement: Set object = Nothing 



RESOLUTION
To avoid receiving the error message mentioned in the "Symptoms" section of this article, create a custom command button on the form to destroy the object and to close the form. To do so, follow these steps:  Open the form in Design View.  Add a command button to the form, and then set the OnClick property of the command button to the following event procedure: Set fObj = Nothing DoCmd.Close </li> Open the form in Form view, and then close the form with the command button. Note that the form closes without error.</li></ol>

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STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

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Steps to Reproduce the Behavior
<ol> Create a new Access database.</li> In the Database window, click Modules under Objects.</li> On the Insert menu, click Class Module. A new module opens.</li>  In the new class module, type the following code: Option Explicit Private WithEvents fForm As Form

Sub Init(pForm As Form) If fForm Is Nothing Then Set fForm = pForm

End If End Sub

Private Sub Class_Initialize Debug.Print "Object is initialized" End Sub

Private Sub Class_Terminate Debug.Print "Object is terminated" End Sub </li> Save the class module as Class1 and close the Visual Basic Editor.</li> In the Database window, click Forms under Objects, and then click Create form in Design View.</li> On the View menu, click Code. A new module opens.</li>  Type the following in the module: Option Compare Database Option Explicit

Private fObj As New Class1

Private Sub Form_Open(Cancel As Integer) On Error GoTo Err_Form_Open fObj.Init Me Exit_Form_Open: Exit Sub Err_Form_Open: Cancel = True MsgBox Err.Description Resume Exit_Form_Open End Sub

Private Sub Form_Close

Set fObj = Nothing End Sub </li> Save the form and view it in Form view.</li> On the File menu, click Close.</li></ol>

Note that either Microsoft Access stops responding, or you see the error message mentioned in the "Symptoms" section.

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