Runtime Changes for Migration from .NET Framework 4.0 to 4.5.2

• 07/10/2019
• 38 minutes to read
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Introduction

Runtime changes affect all apps that are running under a .NET Framework it was not compiled against and that use a particular feature.

In the topics that describe runtime changes, we have classified individual items by their expected impact, as follows:

Major This is a significant change that affects a large number of apps or that requires substantial modification of code.

Minor This is a change that affects a small number of apps or that requires minor modification of code.

Edge case This is a change that affects apps under very specific scenarios that are not common.

Transparent This is a change that has no noticeable effect on the app's developer or user. The app should not require modification because of this change.

If you are migrating from the .NET Framework 4.0 to 4.5.2, review the following topics for application compatibility issues that may affect your app:

ADO.NET

ADO.NET now attempts to automatically reconnect broken SQL connections

ASP.NET

ASP.NET MVC now escapes spaces in strings passed in via route parameters

GridViews with AllowCustomPaging set to true may fire the PageIndexChanging event when leaving the final page of the view

HttpRequest.ContentEncoding property prohibits UTF7

HttpUtility.JavaScriptStringEncode escapes ampersand

IPad should not be used in custom capabilities file because it is now a browser capability

No longer able to set EnableViewStateMac to false

Page.LoadComplete event no longer causes System.Web.UI.WebControls.EntityDataSource control to invoke data binding

Sharing session state with Asp.Net StateServer requires all servers in the web farm to use the same .NET Framework version

WebUtility.HtmlDecode no longer decodes invalid input sequences

Core

A ConcurrentDictionary serialized in .NET Framework 4.5 with NetDataContractSerializer cannot be deserialized by .NET Framework 4.5.1 or 4.5.2

Assemblies compiled with Regex.CompileToAssembly breaks between 4.0 and 4.5

BlockingCollection<T>.TryTakeFromAny does not throw anymore

Change in behavior for Task.WaitAll methods with time-out arguments

Compiler support for type forwarding when multi-targeting mscorlib

COR_PRF_GC_ROOT_HANDLEs are not being enumerated by profilers

Deserialization of objects across appdomains can fail

ETW EventListeners do not capture events from providers with explicit keywords (like the TPL provider)

EventListener truncates strings with embedded nulls

EventSource.WriteEvent impls must pass WriteEvent the same parameters that it received (plus ID)

Exceptions during unobserved processing in System.Threading.Tasks.Task no longer propagate on finalizer thread

List.Sort algorithm changed

Marshal.SizeOf and Marshal.PtrToStructure overloads break dynamic code

Missing Target Framework Moniker results in 4.0 behavior

System.Threading.Tasks.Task no longer throw ObjectDisposedException after object is disposed

System.Uri escaping now supports RFC 3986

WinRT stream adapters no long call FlushAsync automatically on close

using (var stream = GetWindowsRuntimeStream() as Stream)
{
// do something
await stream.FlushAsync();
}

Data

ADO.NET now attempts to automatically reconnect broken SQL connections

Sql_variant data uses sql_variant collation rather than database collation

SqlBulkCopy uses destination column encoding for strings

SqlConnection can no longer connect to SQL Server 1997 or databases using the VIA adapter

Debugger

Null coalescer values are not visible in debugger until one step later

Entity Framework

Change in behavior in Data Definition Language (DDL) APIs

Different exception handling for ObjectContext.CreateDatabase and DbProviderServices.CreateDatabase methods

EF no longer throws for QueryViews with specific characteristics

<add key="EntityFramework_SimplifyUserSpecifiedViews" value="false" />

EntityFramework 6.0 loads very slowly in apps launched from Visual Studio

Log file name created by the ObjectContext.CreateDatabase method has changed to match SQL Server specifications

ObjectContext.Translate and ObjectContext.ExecuteStoreQuery now support enum type

Opt-in break to revert from different 4.5 SQL generation to simpler 4.0 SQL generation

<add key="EntityFramework_SimplifyLimitOperations" value="true" />

LINQ

Enumerable.Empty<TResult> always returns cached instance

Managed Extensibility Framework (MEF)

MEF catalogs implement IEnumerable and therefore can no longer be used to create a serializer

Networking

Deserialization of MailMessage objects serialized under the .NET Framework 4.5 may fail

System.Net.PeerToPeer.Collaboration unavailable on Windows 8

Printing

Data written to PrintSystemJobInfo.JobStream must be in XPS format

Serialization

BinaryFormatter can fail to find type from LoadFrom context

var formatter = new BinaryFormatter { Binder = new TypeFinderBinder() }

public class TypeFinderBinder : SerializationBinder
{
private static readonly string s_assemblyName = Assembly.GetExecutingAssembly().FullName;

public override Type BindToType(string assemblyName, string typeName)
{
return Type.GetType(String.Format(CultureInfo.InvariantCulture, "{0}, {1}", typeName, s_assemblyName));
}
}

NetDataContractSerializer fails to deserialize a ConcurrentDictionary serialized with a different .NET version

SoapFormatter cannot deserialize Hashtable and similar ordered collection objects

XmlSerializer fails while serializing a type that hides an accessible member with an inaccessible one

<system.xml.serialization>
<xmlSerializer useLegacySerializerGeneration="true" />
</system.xml.serialization>

Web Applications

Managed browser hosting controls from the .NET Framework 1.1 and 2.0 are blocked

Windows Communication Foundation (WCF)

Error codes for maxRequestLength or maxReceivedMessageSize are different

MinFreeMemoryPercentageToActiveService is now respected

System.ServiceModel.Web.WebServiceHost object no longer adds a default endpoint

The Replace method in OData URLs is disabled by default

Windows Forms

PreviewLostKeyboardFocus is called repeatedly if its handler shows a Windows Forms message box

WinForm's CheckForOverflowUnderflow property is now true for System.Drawing

Windows Presentation Foundation (WPF)

Accessing a WPF DataGrid's selected items from a handler of the DataGrid's UnloadingRow event can cause a NullReferenceException

Calling Items.Refresh on a WPF ListBox, ListView, or DataGrid with items selected can cause duplicate items to appear in the element

FlowDocument may show an extra line of text

GlyphRun.ComputeInkBoundingBox() and FormattedText.Extent return different values beginning in .NET Framework 4.5

<appsettings>
<add key="IncludeAllInkInBoundingBox" value="false">
</appsettings>

Items.Clear does not remove duplicates from SelectedItems

ListBoxItem IsSelected binding issue with ObservableCollection<T>.Move

New enum values in WPF's PageRangeSelection

PreviewLostKeyboardFocus is called repeatedly if its handler shows a Windows Forms message box

Right clicking on a WPF DataGrid row header changes the DataGrid selection

WPF DataTemplate elements are now visible to UIA

WPF DispatcherSynchronizationContext.CreateCopy now returns a new copy instead of the current instance

WPF spawns a wisptis.exe process which can freeze the mouse

WPF TextBox defaults to undo limit of 100

WPF TextBox selected text appears a different color when the text box is inactive

WPF TreeViewItem must be used within a TreeView

Windows Workflow Foundation (WF)

System.Activities is now APTCA

WF serializes Expressions.Literal<T> DateTimes differently now (breaks custom XAML parsers)

XML, XSLT

XmlSchemaException now sets line positions properly

XmlTextReader DTD entity expansion is limited to 10,000,000 characters

XSLT forward compat now works

XSLT style sheet exception message changed