Breaking changes in .NET 11

If you're migrating an app to .NET 11, 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 runtime. If the new behavior is undesirable, existing code would need to be updated and recompiled.

Note

This article is a work in progress. It's not a complete list of breaking changes in .NET 11.

Core .NET libraries

Title	Type of change
CRC32 validation added when reading ZIP archive entries	Behavioral change
DateOnly and TimeOnly TryParse methods throw for invalid input	Behavioral change
DeflateStream and GZipStream write headers and footers for empty payload	Behavioral change
Environment.TickCount made consistent with Windows timeout behavior	Behavioral change
MemoryStream maximum capacity updated and exception behavior changed	Behavioral change
NamedPipeServerStream with PipeOptions.CurrentUserOnly tightens Unix socket file permissions	Behavioral change
Nullable.GetUnderlyingType throws for custom Type subclasses	Behavioral change
API obsoletions with non-default diagnostic IDs (.NET 11)	Source incompatible
SafeFileHandle.IsAsync and FileStream.IsAsync accurately reflect non-blocking state on Unix	Behavioral change
TAR-reading APIs verify header checksums when reading	Behavioral change
TarWriter uses HardLink entries for hard-linked files	Behavioral change
ZipArchive.CreateAsync eagerly loads ZIP archive entries	Behavioral change

Cryptography

Title	Type of change
DSA removed from macOS	Behavioral change

Extensions

Title	Type of change
IHost.RunAsync and IHost.StopAsync throw when a BackgroundService fails	Behavioral change

Globalization

Title	Type of change
Japanese Calendar minimum supported date corrected	Behavioral change

Interop

Title	Type of change
NativeAOT uses lib prefix for native library outputs on Unix	Behavioral change

JIT compiler

Title	Type of change
Minimum hardware requirements updated	Behavioral change

Networking

Title	Type of change
SslStream server-side AIA certificate downloads disabled by default	Behavioral change

.NET MAUI

Title	Type of change
Minimum Android API level raised to 24	Behavioral change

SDK and MSBuild

Title	Type of change
mono launch target not set for .NET Framework apps	Behavioral change
VSTest removes dependency on Newtonsoft.Json	Binary/source incompatible