.NET Questions and Solutions

Symptoms
In a Microsoft Visual Basic 2005 or Microsoft Visual Basic .NET application, when you pass late-bound parameters to methods of Microsoft Office objects, you may receive COMException exceptions. For example, when you pass the Name property of a late-bound UserProperty object to the UserProperties.Items method, you may receive the following error message:

An unhandled exception of type ‘System.Runtime.InteropServices.COMException’ occurred in microsoft.visualbasic.dll
Additional information: Property is read-only.Note Similar symptoms may also occur when you call methods of other Microsoft Office objects.
Resolution
If you pass a property of an object to a method by reference and the property has a set accessor, Visual Basic calls the set accessor to set the property to the value that the method returns. At compile time, if you pass a property of a late-bound object, the Visual Basic compiler cannot determine whether the property is passed by reference. Also, the Visual Basic compiler cannot determine whether the property has a set accessor. Therefore, the Visual Basic compiler permits the late binder to determine these details at run time.
However, if the relevant objects are Component Object Model (COM) objects at run time, the late binder cannot obtain sufficient information about these details. The late binder uses managed reflection to try to determine these details. The late binder assumes that such method calls involve a ByRef parameter and that the property that you pass has a set accessor. If the property that you pass does not have a set accessor, the Microsoft .NET Framework generates a MissingMethodException exception. The late binder handles the MissingMethodException exception.
The .NET Framework generates a MissingMethodException exception when the call to a method of a Microsoft Office object returns a HRESULT value of COR_E_MISSINGMETHOD. The Microsoft Office object is a COM object. Visual Basic .NET incorrectly assumes that all the methods of Microsoft Office objects return COR_E_MISSINGMETHOD if the property that you pass does not have a set accessor. However, not all the methods of Microsoft Office objects return COR_E_MISSINGMETHOD if the property that you pass does not have a set accessor. Therefore, the behavior that is mentioned in the “Symptoms” section of this article occurs if you pass a property that does not have a set accessor, such as the UserProperty.Name property, to a method.
Note This behavior does not occur if you use early-bound Microsoft Office objects.

Symptoms
When you try to pass a Collection object fromMicrosoft Visual Basic 6.0 components to Microsoft Visual Basic 2005 or to Microsoft Visual Basic .NET, you may receive an error message. In Microsoft Visual Studio 2005, you receive the following error message:

An unhandled exception of type ‘System.InvalidCastException’ occurred in ApplicationName.exe
Additional information: Unable to cast object of type ‘Microsoft.VisualBasic.Collection’ to type ‘VBA.Collection’.In Microsoft Visual Studio .NET, you receive the following error message:

An unhandled exception of type ‘System.InvalidCastException’ occurred in ApplicationName.exe
Additional information: Specified cast is not valid.If you examine the type of the collection object that Visual Basic 2005 or Visual Basic .NET expects, you find that Visual Basic 2005 or Visual Basic .NET expects the VBA.Collection type instead of the Microsoft.VisualBasic.Collection type. If you change your code to pass a collection object of the VBA.Collection type, you receive the following error message on the line of code where you try to create a new instance of the VBA.Collection class:

An unhandled exception of type ‘System.Runtime.InteropServices.COMException’ occurred in ApplicationName.exe
Additional information: COM object with CLSID {A4C4671C-499F-101B-BB78-00AA00383CBB} is either not valid or not registered.This problem also occurs in other Microsoft .NET Framework-supported languages such as Microsoft Visual C# 2005 and earlier versions of .NET Framework-supported Microsoft Visual C#.
Resolution
The InvalidCastException error occurs because the Microsoft.VisualBasic.Collection type is incompatible with the VBA.Collection type. The COMException error occurs because only a Visual Basic 6.0 application can create an instance of the VBA.Collection class. You cannot create an instance of the VBA.Collection class outside a Visual Basic 6.0 application.

Symptoms
Microsoft Visual Basic .NET or Microsoft Visual Basic 2005 allows you to declare static local variables inside a method of class. However, if you declare a static local variable in a method of the Visual Basic .NET or Visual Basic 2005 class, and then you try to serialize the object of the class by using BinaryFormatter or SoapFormatter, you receive the following exception during run time:

An unhandled exception of type ‘System.Runtime.Serialization.SerializationException’ occurred in mscorlib.dll
Additional information: The type Microsoft.VisualBasic.CompilerServices.StaticLocalInitFlag in Assembly Microsoft.VisualBasic, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a is not marked as serialized.
Resolution
The common language runtime does not support static variables in methods. When Visual Basic .NET or Visual Basic 2005 compiler compiles your code, it translates this high-level Visual Basic .NET or Visual Basic 2005 code to Microsoft intermediate language (MSIL) code that the common language runtime can understand to give you shared variable functionality. Visual Basic .NET or Visual Basic 2005 uses the Microsoft.VisualBasic.CompilerServices.StaticLocalInitFlag class to provide this functionality. In Visual Basic .NET or in Visual Basic 2005 compiler, the StaticLocalInitFlag is not marked as serialized. Therefore, you receive the exception during run time.

Symptoms
When you set a public object variable of a Microsoft Component Object Model (COM) component in Microsoft Visual Basic .NET or in Microsoft Visual Basic 2005, you may receive the following error message:

An unhandled exception of type ‘System.Runtime.InteropServices.COMException’ occurred in microsoft.visualbasic.dll
Additional information: Object variable or With block variable not set
Resolution
This behavior can occur if all the following conditions are true: You define a public variable in the COM component.The variable is of the Object type.You reference this COM component by using late binding in Visual Basic .NET or in Visual Basic 2005. When you access the public object by using late binding, Visual Basic .NET or Visual Basic 2005 does not correctly set the BindingFlags enumeration.
The BindingFlags enumeration is used to specify the flags that control binding and the way in which the search for members and types is conducted by reflection.