Introduction
You might have noticed that some of the legacy projects (.NET 4.5 framework) are no longer supported in Visual Studio 2022 directly. We will get some errors while opening those projects.
Because Microsoft is no longer supplying the developer pack (SDK) for .NET framework 4.5 or lower versions now.
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If you are trying to open a legacy .NET 4.5 framework project in Visual Studio 2022, you will get the below warning messages.
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You can update the target to .NET framework 4.8 but it may affect the other people who are still working on the same project with older version of Visual Studio. Also, sometimes it will not work even after you updated the target to 4.8 framework.
But we can download the .NET 4.5 framework in another way. We can download the reference assemblies from the NuGet library given below.
Microsoft.NETFramework.ReferenceAssemblies.net45
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After downloading this package file, you must use any of the file extracting applications to extract above package. Some of the applications like 7-zip support to extract NuGet packages.
7-zip is an open source and free software tool.
https://www.7-zip.org/
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After extracting the package, under build -> .NETFramework folder you can find a v4.5 folder.
Downloads\microsoft.netframework.referenceassemblies.net45.1.0.2\build\.NETFramework\v4.5
You can copy the entire files from this v4.5 folder and paste under the folder below in your machine.
C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5
Above is the current .NET framework 4.5 version folder.
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There are 309 files in the NuGet package folder, and it will replace the existing 120 files in our current .NET 4.5 framework folder.
After replacing the files, we can try to open the legacy project in Visual Studio 2022.
Project will be opened without any issues.
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On some occasions, if you face any error like below you can clean the solution and build again.
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After cleaning and rebuilding the solution, the application will work without any issues.
I am giving credits for this post to Thomas Levesque and his post below.
https://thomaslevesque.com/2021/11/12/building-a-project-that-target-net-45-in-visual-studio-2022/
Conclusion
In this post, we have seen the simple steps to open legacy .NET 4.5 projects in latest Visual Studio 2022. I have attached one legacy application with this post. You can try to open this project in your machine and follow the steps mentioned in the post. If you are still facing some other issues while opening legacy projects in Visual Studio 2022, please feel free to message me here.