Why the class library has different supports for framework and .NET?

Question

Why the class library has different supports for framework and .NET?

Y. Yakir 70

Hi,

I looked on evolution of class library.

It used for reused.

As I see the class library has different supports for Framework and .NET.

Can you please explain it in more details , what are the option and what is roadmap for future ?

Every NuGet packaged that used has to support both Framework and .NET.

Thank in advance,

Koung Koung 0 Reputation points

2026-02-08T07:33:22.6+00:00

Call Methods from the .NET Class Library using C# - Training

2 answers

Your answer

Koung Koung 0 Reputation points

2026-02-08T07:33:22.6+00:00

Call Methods from the .NET Class Library using C# - Training

Answer 1

Thanks for reaching out.
Class libraries have different support because .NET Framework and modern .NET (.NET 5+) are different runtimes with different goals.

.NET Framework is Windows‑only and in maintenance mode. It receives security fixes but no new features. It exists mainly for legacy applications.
Modern .NET (.NET 5+) is the future platform. It is cross‑platform, actively developed, and gets new APIs, performance improvements, and long‑term support (LTS/STS).

Because the available APIs differ, a single binary cannot always work for both runtimes.

Recommended options:

Multi‑targeting (recommended) Build one library that targets multiple frameworks (for example net48; net8.0). NuGet automatically selects the correct version for the consumer.
.NET Standard (limited today) Useful only if you need broad compatibility with older platforms, but it is frozen and not recommended for new development.
Separate libraries/packages Use this when you depend on runtime‑specific or Windows‑only APIs.

Roadmap:

.NET Framework will continue to be supported with Windows but will not get new features.
Modern .NET is Microsoft’s strategic direction and should be used for all new libraries and applications.

Important: Not every NuGet package must support both .NET Framework and modern .NET. Multi‑targeting is the correct and supported approach when you need to support both.

Let us know if the issue persists after following these steps. I’ll be happy to assist further if needed. If the issue has been resolved, Kindly mark the provided solution as "Accept Answer", so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

Y. Yakir 70 Reputation points

2026-02-06T13:27:58.9233333+00:00

If I used modern .NET platform which Target Frameworks to use:

<TargetFrameworks>net6.0</TargetFrameworks> or older or higher ?

Does Target Framework netstandard2.1 is older NET Framework**?**

<TargetFramework>netstandard2.1</TargetFramework>
Bruce (SqlWork.com) 83,501 Reputation points Volunteer Moderator

2026-02-07T18:30:09.2133333+00:00

if you need to share the library with the old framework and core then use .netstandard 2.0. this option supports c# 7.3 syntax

if the library is for core, and you want minimum maintenance then you can use .netstandard 2.1. this option supports c# 8.0

if the library is for core you can use the same framework as the hosting project, this will give you the same api and c# version the hosting project

if the library is for multiple core versions (say 8.0 & 10.0), you can build a multi-target library and build a release for each framework version (this is common with nuget packages). you may need conditional compile for breaking changes in framework versions.

Answer 2

kagiyama yutaka 1,165

I think the split is mostly ’cause we still run code from years back… so libs keep two TFMs just to not disturb some old system that can’t move anymore. nugets follow that.

Gade Harika (INFOSYS LIMITED) 2,590 Reputation points Microsoft External Staff

2026-02-10T07:48:47.6833333+00:00

Thanks for reaching out,
Yes, that’s essentially the reason. Many libraries keep multiple target frameworks (TFMs) to continue supporting legacy applications that can’t be upgraded, while still enabling newer apps to run on modern .NET. Multi‑targeting lets the same NuGet package serve both old and new systems without breaking existing deployments, and NuGet automatically selects the correct build for each consumer. This is a compatibility and risk‑management decision—not a technical requirement—and it’s why you often see libraries targeting both .NET Framework and modern .NET in parallel.
Gade Harika (INFOSYS LIMITED) 2,590 Reputation points Microsoft External Staff

2026-02-12T09:57:45.9833333+00:00

Hope you’re doing well. We’re following up on this thread to check if the issue is still occurring or has been resolved. If it has been resolved, kindly mark the answer as accepted. We will proceed with thread closure by Feb 13th
G S 0 Reputation points

2026-02-13T06:07:19.21+00:00

If I I run only modern apps .NET 10, so all my class libraries and client should be in .NET 10 ?
Gade Harika (INFOSYS LIMITED) 2,590 Reputation points Microsoft External Staff

2026-02-13T07:54:27.38+00:00

Thanks for reaching out.
If your solution is .NET 10-only (all apps/clients that reference your libraries run on .NET 10), then you can simply target everything to net10.0. That’s the base TFM recommended for most libraries, and you only need a platform-specific TFM like net10.0-windows if the library uses Windows-only APIs. If you need the same library to be consumed by older .NET / .NET Framework apps, then target netstandard2.0 (or multi-target net10.0;netstandard2.0) so those older consumers can still reference it. [Target fra...soft Learn | Learn.Microsoft.com] [Port from...soft Learn | Learn.Microsoft.com]
Gade Harika (INFOSYS LIMITED) 2,590 Reputation points Microsoft External Staff

2026-02-16T12:08:00.13+00:00

We haven’t received any further updates or follow-up on this case, so we’ll proceed with closing it at this time. If you require additional assistance or have new information to share, please feel free to raise new thread, we’re happy to support you further needed.

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Why the class library has different supports for framework and .NET?

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