Microsoft has put up a doc at the MSDN site which contains all the breaking changes from Beta 2 to the RTM version.
Table of Contents
Breaking Changes in Visual Studio and the .NET Framework
Breaking Changes Overview
Functional Areas
.NET Framework Version 2.0
Threading Cancellation
Functionality
INullableValue Interface
System.Nullable<T>
Boxing and Unboxing of Nullable<T>
.NET Client
MenuCommands Class
Behavior Class
ColumnWidthChangedEventArgs Class
BindingContext Class
DataGridViewRow Class
DataGridViewCell Class
Client Application User Settings
Application Settings Serialization
TreeView and TreeNode Classes
BackgroundWorker Class
MaskedTextBox Class
GetPreferredSize Property of Form
Controls
Windows Forms API Changes
CancelRowEdit Event
AsyncCompletedEventArgs.Error
Property
RadioButton.TabStop Property
MDI Automatic Merging
BindingSource.Items Property
.NET Compact Framework
EventArgs Classes
Common Language Runtime (CLR)
X509Certificate2UI Class
System.Threading.Thread Class
KeyValuePair Class
AssembliesVisibleTo Attribute
System.Data Namespace
SqlDataReader.GetSchemaTable
Method
SqlNotificationEncryptionType
Enumeration
System.Data.SqlTypes.SqlStreamChars
Property
SqlDataReader.GetSqlValue Return
Type
Globalization
Persian Calendar Class
DateTimeFormatInfo Class
Visual Studio Tools for Office
VSTView Interface
Visual C++ Programming Language
ATL Server — CAtlHttpClient
Class
Floating-point Control Word
Support Functions
Dynamic Cast from Private Base
MFC Wrapper for LoadLibraryEx()
MFC 64-bit Message Map Support
C# Programming Language
Compilation Error Due to Implicit
Conversion
Checked and Unchecked Expressions
Nullable<T> Does Not Satisfy
IComparable Constraint Error
Cannot Form a Delegate Over
Nullable<T> Error
Operator "is" Returns
true for T and Non-null T?
Visual Basic Programming Language
TypeOf Statement
Non-CLS Compliant Return Types
Overriding Object Members in
Structures
Namespaces with Different Casing
Implementing MustOverride Methods
AppActivate Case-insensitivity
AppActivate Right-Hand Title
CreateObject Case-insensitivity
Zero-Based Collection Object
FileIO Enumerations
FileLogTraceListener.CustomLocation
Property
FileLogTraceListener Date Format
ClickOnce Runtime Process
ClickOnce Store Change
WebBrowser Permissions
Visual Studio
Visual Studio Settings
Machine.config File Changes
Visual C++ Beta 2 Project Open
Error
Errors When Deploying Device
Projects to the Device Emulator
ASP.NET
Unique Class Names
HTML Default Validation Schema
Events for Non-Visible Controls
ICallbackEventHandler.GetCallbackResult
Method
ASP.NET Personalization Database
Schema
Page.CreateStateFormatter Method
Aspnet_regiis.exe Utility Argument
Change
WebPart File Format
System.Web.UI.IPageHeader
Relative References in the
Configuration File
Web Project Global Settings and Project Policy Settings
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