Breaking changes in .NET 7

If you're migrating an app to .NET 7, the breaking changes listed here might affect you. Changes are grouped by technology area, such as ASP.NET Core or Windows Forms.

This article categorizes each breaking change as binary incompatible or source incompatible, or as a behavioral change:

• Binary incompatible - When run against the new runtime or component, existing binaries may encounter a breaking change in behavior, such as failure to load or execute, and if so, require recompilation.

• Source incompatible - When recompiled using the new SDK or component or to target the new runtime, existing source code may require source changes to compile successfully.

• Behavioral change - Existing code and binaries may behave differently at run time. If the new behavior is undesirable, existing code would need to be updated and recompiled.

ASP.NET Core

Title	Type of change
API controller actions try to infer parameters from DI	Source incompatible
ASPNET-prefixed environment variable precedence	Behavioral change
AuthenticateAsync for remote auth providers	Source incompatible
Authentication in WebAssembly apps	Binary incompatible
Default authentication scheme	Binary incompatible
Event IDs for some Microsoft.AspNetCore.Mvc.Core log messages changed	Binary incompatible
Fallback file endpoints	Binary incompatible
IHubClients and IHubCallerClients hide members	Source incompatible
Kestrel: Default HTTPS binding removed	Binary incompatible
Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv and libuv.dll removed	Binary/source incompatible
Microsoft.Data.SqlClient updated to 4.0.1	Source incompatible
Middleware no longer defers to endpoint with null request delegate	Binary incompatible
MVC's detection of an empty body in model binding changed	Binary incompatible
Output caching API changes	Binary/source incompatible
SignalR Hub methods try to resolve parameters from DI	Source incompatible

Core .NET libraries

Title	Type of change
API obsoletions with default diagnostic ID	Source incompatible
API obsoletions with non-default diagnostic IDs	Source incompatible
Asterisk no longer accepted for assembly name attributes	Behavioral change
BinaryFormatter serialization APIs produce compiler errors	Source incompatible
BrotliStream no longer allows undefined CompressionLevel values	Binary incompatible
C++/CLI projects in Visual Studio	Source incompatible
Changes to reflection invoke API exceptions	Binary incompatible
Collectible Assembly in non-collectible AssemblyLoadContext	Binary incompatible
DateTime addition methods precision change	Behavioral change
Equals method behavior change for NaN	Binary incompatible
EventSource callback behavior	Behavioral change
Generic type constraint on PatternContext<T>	Binary/source incompatible
Legacy FileStream strategy removed	Binary incompatible
Library support for older frameworks	Binary/source incompatible
Maximum precision for numeric format strings	Binary incompatible
Regex patterns with ranges corrected	Behavioral change
SerializationFormat.Binary is obsolete	Binary/source incompatible
System.Drawing.Common config switch removed	Behavioral change
System.Runtime.CompilerServices.Unsafe NuGet package	Behavioral change
Time fields on symbolic links	Binary incompatible
Tracking linked cache entries	Binary incompatible
Validate CompressionLevel for BrotliStream	Binary incompatible

Configuration

Title	Type of change
System.diagnostics entry in app.config	Binary incompatible

Cryptography

Title	Type of change
Decrypting EnvelopedCms doesn't double unwrap	Binary incompatible
Dynamic X509ChainPolicy verification time	Binary incompatible
X500DistinguishedName parsing of friendly names	Binary incompatible

Deployment

Title	Type of change
All assemblies trimmed by default	Source incompatible
Multi-level lookup is disabled	Binary incompatible
x86 host path on 64-bit Windows	Behavioral change
TrimmerDefaultAction is deprecated	Source incompatible

Entity Framework Core

Breaking changes in EF Core 7

Extensions

Title	Type of change
Binding config to dictionary extends values	Behavioral change
ContentRootPath for apps launched by Windows Shell	Binary incompatible
Environment variable prefixes	Binary incompatible

Globalization

Title	Type of change
Globalization APIs use ICU libraries on Windows Server	Binary incompatible

Interop

Title	Type of change
RuntimeInformation.OSArchitecture under emulation	Binary incompatible

.NET MAUI

Title	Type of change
Constructors accept base interface instead of concrete type	Binary incompatible
Flow direction helper methods removed	Binary/source incompatible
New UpdateBackground parameter	Binary incompatible
ScrollToRequest property renamed	Binary/source incompatible
Some Windows APIs are removed	Binary/source incompatible

Networking

Title	Type of change
AllowRenegotiation default is false	Binary/source incompatible
Custom ping payloads on Linux	Binary incompatible
Socket.End methods don't throw ObjectDisposedException	Binary incompatible

SDK and MSBuild

Title	Type of change
Automatic RuntimeIdentifier for publish only	Binary/source incompatible
CLI console output uses UTF-8	Binary/source incompatible
Console encoding not UTF-8 after completion	Binary incompatible
MSBuild serialization of custom types in .NET 7	Binary/source incompatible
Side-by-side SDK installations	Binary/source incompatible
Tool manifests in root folder	Behavioral change
Version requirements for .NET 7 SDK	Behavioral change
dotnet test: switch -a to alias --arch instead of --test-adapter-path	Binary/source incompatible
dotnet test: switch -r to alias --runtime instead of --results-dir	Binary/source incompatible
--output option no longer is valid for solution-level commands	Binary/source incompatible
SDK no longer calls ResolvePackageDependencies	Source incompatible

Serialization

Title	Type of change
DataContractSerializer retains sign when deserializing -0	Binary incompatible
Deserialize Version type with leading or trailing whitespace	Binary incompatible
JsonSerializerOptions copy constructor includes JsonSerializerContext	Binary incompatible
Polymorphic serialization for object types	Binary incompatible
System.Text.Json source generator fallback	Binary incompatible

Windows Forms

Title	Type of change
Obsoletions and warnings	Source incompatible
Some APIs throw ArgumentNullException	Binary incompatible

WPF

Title	Type of change
Restored drag-and-drop operations behavior on text editors	Behavioral change

XML and XSLT

Title	Type of change
XmlSecureResolver is obsolete	Binary/source incompatible

See also

• C# compiler breaking changes in C# 11 / .NET 7
• What's new in .NET 7