MessagePack.Annotations 4.0.0-preview.1

.NET Standard 2.0 This package targets .NET Standard 2.0. The package is compatible with this framework or higher.
This is a prerelease version of MessagePack.Annotations. 
dotnet add package MessagePack.Annotations --version 4.0.0-preview.1
                    


                    

                
NuGet\Install-Package MessagePack.Annotations -Version 4.0.0-preview.1
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package. 
<PackageReference Include="MessagePack.Annotations" Version="4.0.0-preview.1" />
For projects that support PackageReference, copy this XML node into the project file to reference the package. 
<PackageVersion Include="MessagePack.Annotations" Version="4.0.0-preview.1" />
                    


                            Directory.Packages.props
                        

                    

                
<PackageReference Include="MessagePack.Annotations" />
                    


                            Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package. 
paket add MessagePack.Annotations --version 4.0.0-preview.1
                    


                    

                
#r "nuget: MessagePack.Annotations, 4.0.0-preview.1"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package. 
#:package MessagePack.Annotations@4.0.0-preview.1
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package. 
#addin nuget:?package=MessagePack.Annotations&version=4.0.0-preview.1&prerelease
                    


                            Install as a Cake Addin
                        

                    

                
#tool nuget:?package=MessagePack.Annotations&version=4.0.0-preview.1&prerelease
                    


                            Install as a Cake Tool

MessagePack.Annotations (migration shim)

In MessagePack v4 the attributes ([MessagePackObject], [Key], [IgnoreMember], [SerializationConstructor], [MessagePackFormatter]) and IMessagePackSerializationCallbackReceiver live in the MessagePack package itself. The source generator ships there too and runs on the assembly that declares the annotated types, so that assembly has to reference MessagePack anyway. An annotations-only reference is no longer a supported setup.

This package exists so that projects coming from v3 keep working:

  • The surviving types are type-forwarded to MessagePack, so using MessagePack; code compiles unchanged and the attribute types a pre-built v3 assembly references resolve (its formatter code, bound to v3's reader and writer, still cannot run on v4).
  • The package depends on MessagePack, so bumping its version brings the v4 runtime and source generator in.
  • Referencing the 4.x version keeps MessagePack.Annotations 3.x from sitting next to MessagePack 4.x, which would define every attribute twice (CS0433). NuGet does not do this on its own: MessagePack does not depend on this package (the dependency runs the other way), so a transitive 3.x reference from a v3-built library stays at 3.x until the consuming project adds an explicit PackageReference to MessagePack.Annotations 4.x.
  • The types v4 renamed or deleted ([Union], [MessagePackKnownFormatter], [MessagePackAssumedFormattable], [ExcludeFormatterFromSourceGeneratedResolver]) still exist here in their v3 shape, marked [Obsolete] with error: true. The compiler error text tells you the replacement.

Once your code compiles, remove this package and reference MessagePack directly.

Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed.  net9.0 was computed.  net9.0-android was computed.  net9.0-browser was computed.  net9.0-ios was computed.  net9.0-maccatalyst was computed.  net9.0-macos was computed.  net9.0-tvos was computed.  net9.0-windows was computed.  net10.0 was computed.  net10.0-android was computed.  net10.0-browser was computed.  net10.0-ios was computed.  net10.0-maccatalyst was computed.  net10.0-macos was computed.  net10.0-tvos was computed.  net10.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages (94)

Showing the top 5 NuGet packages that depend on MessagePack.Annotations:

Package Downloads
Microsoft.VisualStudio.Utilities

A member of the Visual Studio SDK
Microsoft.VisualStudio.Shell.Framework

A member of the Visual Studio SDK
Microsoft.VisualStudio.Shell.15.0

A member of the Visual Studio SDK
Microsoft.VisualStudio.Imaging

A member of the Visual Studio SDK
Microsoft.VisualStudio.ComponentModelHost

Package Description

GitHub repositories (18)

Showing the top 18 popular GitHub repositories that depend on MessagePack.Annotations:

Repository Stars
Cysharp/MagicOnion
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Source Generator based Embedded Typed Readonly In-Memory Document Database for .NET and Unity.
SteveDunn/Vogen
A semi-opinionated library which is a source generator and a code analyser. It Source generates Value Objects
SparkDevNetwork/Rock
An open source CMS, Relationship Management System (RMS) and Church Management System (ChMS) all rolled into one.
RazorGenerator/RazorGenerator
A Custom Tool for Visual Studio that allows processing Razor files at design time instead of runtime, allowing them to be built into an assembly for simpler reuse and distribution.
AscensionGameDev/Intersect-Engine
Intersect provides a complete game development suite for creating 2d mmorpgs with no programming experience required!
purelogiccode/SimpleLauncher
Simple Launcher is an open-source emulator frontend. Designed for both casual gamers and power users, it provides a seamless interface to organize, browse, and launch your retro gaming collection with deep integration for modern emulators and RetroAchievements.
irsdl/ysonet
Deserialization payload generator for a variety of .NET formatters
carlreid/StreamMaster
A powerful M3U proxy and stream management platform for Plex DVR, Emby, Jellyfin Live TV (and more)
OpenMLTD/MLTDTools
Tools for THE iDOLM@STER Million Live! Theater Days (MLTD/MiriShita/ミリシタ) / 偶像大师百万演唱会剧场时光工具箱
suncloudsmoon/TextCraft
Integrates AI tools into Microsoft Word
akpaevj/oneswiss
Система обслуживания и мониторинга информационных баз 1С
moonheart/mementomori-helper
メメントモリ MementoMori 游戏助手 Game Assistant ゲームアシスタント
Cysharp/GrpcWebSocketBridge
Yet Another gRPC over HTTP/1 using WebSocket implementation, primarily targets .NET platform.
DigitalPlatform/dp2
Integrated Library System / 图书馆集成系统
rubberduck-vba/Rubberduck3
COM add-in for the VBIDE
beetlex-io/BeetleX-Samples
BeetleX micro services framework (tcp webapi websocket and xrpc) samples
Version Downloads Last Updated
4.0.0-preview.1 32 10/22/2026
3.1.12 371,681 10/12/2026
3.1.11 297,838 10/3/2026
3.1.10 479,851 9/23/2026
3.1.9 366,643 9/17/2026
3.1.8 4,738,864 7/8/2026
3.1.7 7,582,130 6/9/2026
3.1.6 418,705 5/21/2026
3.1.5 23,173 5/21/2026
3.1.4 16,522,619 6/12/2025
3.1.3 8,101,901 2/4/2025
3.1.2 710,303 1/27/2025
3.1.1 3,774,263 12/26/2024
2.5.307 357,115 10/3/2026
2.5.305 85,047 9/23/2026
2.5.303 571,958 9/17/2026
2.5.302 13,480,361 6/9/2026
2.5.301 5,240,919 6/9/2026
2.5.205 24,133 5/21/2026
2.5.198 2,687,401 4/10/2025
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