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:

• Binary incompatible - Existing binaries may encounter a breaking change in behavior, such as failure to load or execute, or different run-time behavior.
• Source incompatible - Source code may encounter a breaking change in behavior when targeting the new runtime or using the new SDK or component. Behavior changes can include compile errors or different run-time behavior.

Note

This article is a work in progress. It's not a complete list of breaking changes in .NET 7. To query breaking changes that are still pending publication, see Issues of .NET.

ASP.NET Core

Title	Binary compatible	Source compatible	Introduced
API controller actions try to infer parameters from DI	✔️	❌	Preview 2
Default authentication scheme	❌	✔️	Preview 7
Event IDs for some Microsoft.AspNetCore.Mvc.Core log messages changed	❌	✔️	Preview 3
IHubClients and IHubCallerClients hide members	✔️	❌
Kestrel: Default HTTPS binding removed	❌	✔️	Preview 6
Microsoft.AspNetCore.Server.Kestrel.Transport.Libuv and libuv.dll removed	❌	❌	Preview 1
Microsoft.Data.SqlClient updated to 4.0.1	✔️	❌	Preview 2
Middleware no longer defers to endpoint with null request delegate	❌	✔️	Preview 7
MVC's detection of an empty body in model binding changed	❌	✔️	Preview 3
SignalR Hub methods try to resolve parameters from DI	✔️	❌	Preview 2

Core .NET libraries

Title	Binary compatible	Source compatible	Introduced
API obsoletions with non-default diagnostic IDs	✔️	❌	Preview 1
BinaryFormatter serialization APIs produce compiler errors	✔️	❌	RC 1
C++/CLI projects in Visual Studio	✔️	❌	Preview 3
Changes to reflection invoke API exceptions	❌	✔️	Preview 4
Collectible Assembly in non-collectible AssemblyLoadContext	❌	✔️	Preview 5
Equals method behavior change for NaN	❌	✔️	Preview 5
Generic type constraint on PatternContext<T>	❌	❌	Preview 3
SerializationFormat.Binary is obsolete	❌	❌	Preview 2
Validate CompressionLevel for BrotliStream	❌	✔️	Preview 1

Cryptography

Title	Binary compatible	Source compatible	Introduced
Decrypting EnvelopedCms doesn't double unwrap	❌	✔️	Preview 5
Dynamic X509ChainPolicy verification time	❌	✔️	Preview 7
X500DistinguishedName parsing of friendly names	❌	✔️	Preview 5

Deployment

Title	Binary compatible	Source compatible	Introduced
All assemblies trimmed by default	✔️	❌	Preview 7
Multi-level lookup is disabled	❌	✔️	Preview 4
x86 host path on 64-bit Windows	✔️	✔️	Preview 6

Extensions

Title	Binary compatible	Source compatible	Introduced
ContentRootPath for apps launched by Windows Shell	❌	✔️	Preview 6

Networking

Title	Binary compatible	Source compatible	Introduced
AllowRenegotiation default is false	❌	❌	Preview 3
Custom ping payloads on Linux	❌	✔️	Preview 2

SDK and MSBuild

Title	Binary compatible	Source compatible	Introduced
Version requirements for .NET 7 SDK	✔️	✔️	7.0.100
MSBuild serialization of custom types in .NET 7	❌	❌	7.0.100

Serialization

Title	Binary compatible	Source compatible	Introduced
Deserialize Version type with leading or trailing whitespace	❌	✔️	Preview 1

Windows Forms

Title	Binary compatible	Source compatible	Introduced
Some APIs throw ArgumentNullException	❌	✔️	Preview 1