If you are upgrading a document-level customization, there is no way to prevent the wizard from upgrading the project version. This is because the designer that appears when you open a document-level customization uses the currently installed version of Office. The project can open in the designer only if it matches the version of Office that is installed.

To upgrade a document-level customization project, you must have the appropriate Office application installed. For example, you must have Word 2003 or Word 2007 installed on your computer before you can upgrade a Word 2003 document-level customization project.

If you have the 2007 Microsoft Office system installed, the Visual Studio Conversion Wizard requires you to choose whether you want to convert the document to one of the Open XML Formats. You should convert the format of the document unless you have a specific reason to use the older format. For more information about these formats, see Introduction to new file name extensions and Open XML Formats.

If you have Microsoft Office 2003 installed when you upgrade the project, the project will continue to use Microsoft Office 2003 as the target version and the format of the document will remain the same.

If you upgrade a document-level project that you created by using Visual Studio Tools for Office, Version 2003, you must perform some upgrade steps manually. For more information, see Upgrading from Visual Studio Tools for Office, Version 2003.

If you have the 2007 Microsoft Office system installed, and you do not want the Visual Studio Conversion Wizard to upgrade version 2003 add-in projects to version 2007 add-in projects, you can change the default so they remain Office 2003 projects. Since the 2007 release of Office can host Office 2003 add-ins, you can develop, compile, and test the project even though you do not have Microsoft Office 2003 installed. Clear the Always upgrade to installed version of Office option in the Project Upgrade options page. For more information, see Project Upgrade, Options Dialog Box.

The Visual Studio Conversion Wizard cannot make add-in projects compatible with a previous version of Office. Therefore, if you have Office 2003 installed and upgrade a version 2007 add-in project, then the project remains a version 2007 add-in project after the upgrade is complete. You can open the project, develop the add-in, and compile code successfully. However, you cannot test the add-in because Office 2003 does not host version 2007 add-ins.

You do not need to have Microsoft Office installed to upgrade an application-level add-in project.

The Visual Studio Conversion Wizard does not update the name of your host item class. The name of the class continues to be ThisApplication. You do not need to change this name. However, code examples in the Visual Studio Tools for the Office system 3.0 Help documentation use the host item class name ThisAddIn. If you would like to make it easier to test code by copying it and pasting it in your own project, you can change the name of the class to ThisAddIn and then refactor this name change throughout the project. For information about how to refactor code in a C# project, see How to: Rename Identifiers. For information about how to refactor code in a Visual Basic project, see How to: Rename an Identifier.

The Visual Studio Conversion Wizard does not modify your code. Therefore, you must manually change all code that uses either of the following techniques to access the Application object:

• The this (in C#) or Me (in Visual Basic) keyword inside the ThisApplication class.

• The Globals.ThisApplication object in code outside the ThisApplication class.

For example, if your ThisApplication class contains the following code, you must update it.

Me.ActiveExplorer()

this.ActiveExplorer();

The following code works as the replacement in upgraded projects.

Me.Application.ActiveExplorer()

This.Application.ActiveExplorer();

The ThisApplication host item class in Microsoft Visual Studio 2005 Tools for the Microsoft Office System projects inherits directly from the Microsoft.Office.Tools.Outlook.Application class. However, the ThisAddIn host item class in Visual Studio Tools for the Office system 3.0 projects does not inherit from Microsoft.Office.Tools.Outlook.Application. Instead, you reference the active application object by using the Application property of the host item class.