Open .net framework 4.5 project in VS 2022. Is there any workaround?

Question

Is there anyway to open and work on .net framework 4.5 project in visual studio 2022.

May be problem is not with VS2022 but as .net framework 4.5 developer pack is not available any more .. my project can not be changed target version .. Is there any workaround?

Solution 1

• Download Microsoft.NETFramework.ReferenceAssemblies.net45 from nuget.org
• Open the package as zip
• copy the files from build\.NETFramework\v4.5\ to C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5

For more details: Building a project that target .NET Framework 4.5 in Visual Studio 2022

Solution 2

While all of the proposed, and even the accepted, solutions will work, none of them are the preferred approach.

The only thing you need to do is add a reference to the NuGet package as follows:

<ItemGroup>
 <PackageReference Include="microsoft.netframework.referenceassemblies.net45"
                   Version="1.0.2" PrivateAssets="All" />
</ItemGroup>

You can make this change directly in the *.csproj or via the Package Manager UI in Visual Studio. The MSBuild extensions in the package will take care of the rest of the magic. There are no scripts to write, files to copy, or permissions to grant. This will work without elevation, which would be required to write under %PROGRAMFILES%.

Setting PrivateAssets="All" will make the package reference design-time only. It will not be picked up or included as a transitive dependency if your target also builds a NuGet package.

Roslyn Issue 56161: Remove .NET 4.5 Targeting Pack Requirement further confirms that this how you use reference assemblies when a targeting pack is not installed. This approach is useful any time you don't want to install a targeting pack or it's otherwise unavailable - say on a build server without Visual Studio.

I ran into the same issue after uninstalling Visual Studio 2019. The build worked as expected from Visual Studio and the CLI after adding this package reference.

Solution 3

Here is an automated solution. It follows the steps in this answer: https://stackoverflow.com/a/70109092/569302 When it copies the files a dialog may appear that you have to click to replace files that already exist

(Note: You may need to update the "version" "1.0.2" to whatever is latest if there's a newer NuGet package)

Run await DevHelpers.Download();

using Microsoft.VisualBasic.FileIO;
using System;
using System.Collections.Generic;
using System.IO.Compression;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;

namespace j.Dev
{
    public class DevHelpers
    {
        public static async Task Download()
        {
            var version = "1.0.2";
            var name = "Framework45-" + DateTimeToFileString(DateTime.Now);
            var fileName = $"{name}.zip";
            var url = $"https://www.nuget.org/api/v2/package/Microsoft.NETFramework.ReferenceAssemblies.net45/{version}";
            await DownloadFile(fileName, url);
            ZipFile.ExtractToDirectory(fileName, name);
            var from = Path.Join(name, @"build\.NETFramework\v4.5\");
            var to = @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5";
            FileSystem.CopyDirectory(from, to, UIOption.AllDialogs);
        }

        private static string DateTimeToFileString(DateTime d)
        {
            return d.ToString("yyyy-dd-M--HH-mm-ss");
        }

        private static async Task DownloadFile(string fileName, string url)
        {
            var uri = new Uri(url);
            HttpClient client = new HttpClient();
            var response = await client.GetAsync(uri);
            using (var fs = new FileStream(
                fileName,
                FileMode.CreateNew))
            {
                await response.Content.CopyToAsync(fs);
            }
        }
    }
}

In my case I needed to download 4.0 AND 4.5, so here is the code that downloads both 4.0 and 4.5:

using Microsoft.VisualBasic.FileIO;
using System.IO.Compression;

namespace j.Dev
{
    /// <summary>
    /// Example Usage: await DevHelpers.DownloadAndCopyFramework4_0And4_5();
    /// </summary>
    public class DevHelpers
    {
        public static async Task DownloadAndCopyFramework4_0And4_5()
        {
            await DownloadAndCopyFramework4_0();
            await DownloadAndCopyFramework4_5();
        }

        public static async Task DownloadAndCopyFramework4_5()
        {
            await DownloadAndCopyFrameworkGeneric("net45", "v4.5", "1.0.2");
        }

        public static async Task DownloadAndCopyFramework4_0()
        {
            await DownloadAndCopyFrameworkGeneric("net40", "v4.0", "1.0.2");
        }

        public static async Task DownloadAndCopyFrameworkGeneric(string netVersion, string folder, string nugetVersion)
        {
            var name = netVersion + "-" + DateTimeToFileString(DateTime.Now);
            var fileName = $"{name}.zip";
            var url = $"https://www.nuget.org/api/v2/package/Microsoft.NETFramework.ReferenceAssemblies.{netVersion}/{nugetVersion}";
            await DownloadFile(fileName, url);
            ZipFile.ExtractToDirectory(fileName, name);
            var from = Path.Join(name, @"build\.NETFramework\" + folder);
            var to = @"C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\" + folder;
            FileSystem.CopyDirectory(from, to, UIOption.AllDialogs);
        }

        private static string DateTimeToFileString(DateTime d)
        {
            return d.ToString("yyyy-dd-M--HH-mm-ss");
        }

        private static async Task DownloadFile(string fileName, string url)
        {
            var uri = new Uri(url);
            HttpClient client = new HttpClient();
            var response = await client.GetAsync(uri);
            using (var fs = new FileStream(
                fileName,
                FileMode.CreateNew))
            {
                await response.Content.CopyToAsync(fs);
            }
        }
    }
}

Solution 4

For .NET 4.0, this command will install it for you if you have the Visual Studio 2019 files cached:

msiexec.exe /i "%ALLUSERSPROFILE%\Microsoft\VisualStudio\Packages\Microsoft.Net.4.TargetingPack,version=4.0.30319.1\netfx_dtp.msi" EXTUI=1

For .NET 4.5, this might work, though I haven't tried it:

msiexec.exe /i "%ALLUSERSPROFILE%\Microsoft\VisualStudio\Packages\Microsoft.Net.4.5.2.TargetingPack,version=4.5.51651.1\netfx_452mtpack.msi" EXTUI=1

View more solutions

Comments

[Panagiotis Kanavos]

Upgrade. .NET Framework 4.5 went out of support years ago. The earliest supported version is 4.5.2 but even that goes out of support in a few months. The lowest supported version will be 4.6.2

[Shleemypants]

See: thomaslevesque.com/2021/11/12/…

[Roland]

Important topic. I found the accepted answer good, but still got 4.5.1 from the above screenshot. And will upgrade soon to e.g. 4.8 to be supported, and future-proof.

[Moumit]

OMG it was that easy!! I gone through the link but missed the download package point .. thanks for the step by step simplification ... it's now working

[Jesus is Lord]

I automated the steps in this answer: stackoverflow.com/a/70398706/569302

[Death GOD 7]

Thanks for the script. I wanted both 4.0 and 4.5 as I have old projects for the class library and Winform app. One question : Does the "var version = "1.0.2" or ("netx0", "vx.0", "1.0.2") matter and is it latest as of today (even though the framework version in old)?

[Jesus is Lord]

"Thanks for the script." You're welcome!!!

[Jesus is Lord]

"Does the "var version = "1.0.2" or ("netx0", "vx.0", "1.0.2") matter" If I understand correctly: I provided two code solutions. It doesn't matter if you use the first (var version = "1.0.2") or the second (("net45", "v4.5", "1.0.2")). I provided both because the first answers the question on this site precisely and the second may be helpful to others who are Googling.

[Jesus is Lord]

"is it latest as of today (even though the framework version in old)" As of today it is the most recent NuGet package on this website: nuget.org/packages/… If you click "Versions" you can see the latest (Screenshot of NuGet website: ibb.co/Pc43zG5). An enhancement to the code I've written is to check that NuGet website (or do something) to see if there's a newer NuGet package version

[Jesus is Lord]

@DeathGOD7 See comments above

[Death GOD 7]

Thanks again. I was nearly going for updating the assembly version when I saw 4.0 and 4.5 were gone in VS2022. Then I saw your response and it is good now.

[pink li]

This also works when targeting .Net 4.0, just download the .net40 nuget package, and copy files to \.NETFramework\v4.0 folder. Restart VS then open the project and it works just fine.

[Raju Ahmed]

Note: After downloading you've to rename the file name from .nupkg to .zip than the rest of the process is as mentioned in this answer. Maybe it is known to the maximum of you but It could save hours for someone like me. That's why putting the comment here.

[ahdung]

Thank you very much, you saved me, this is the perfect way. Note the "EXTUI=1" parameter is important.

[Andrew Corrigan]

Question. What if the web app in question doesn't actually contain a csproj file? Surely then, if you can't open the project to use the package manager UI; you're screwed?

[Chris Martinez]

The original question indicated C# and, hence, *.csproj. This approach, however, will work for any MSBuild project be it *.vbproj or a vanilla *.proj. Ultimately, you just need NuGet support. If you're using an older project system or have no project file at all, then you can use the NuGet CLI (e.g. nuget.exe) with packages.config to install the package locally. If you're compiling .NET code with a Web App, MSBuild must be involved somewhere because that's how the compiler is integrated. Connecting package *.targets to your app will enable the magic.

[user10191234]

It does not work for .Net 3.5

[Olanrewaju O. Joseph]

Remember to close and re-open Visual Studio after this as the change doesn't automatically take effect.

[Olanrewaju O. Joseph]

This also works for .Net Framework 4.5.1 and for any other version. Just get the Nuget package for the version of .Net framework you need, and unzip and copy the files in the corresponding folder on your PC

[Dennis]

Even if you have a v4.5 folder already, move those files to a new folder _BK and paste the files into the v4.5 folder. Works perfect. thank you!

[FryGuy]

I wish this answer was the accepted one.

[Chris Martinez]

Despite this being the Accepted answer, it is honestly the hard way. The one and only thing you need to do is reference the appropriate NuGet package. You do not need to explicitly download, extract it, or write any code for it to work. It will work with any project that supports NuGet or packages.config. The issue with this approach is that it requires elevation to write to a protected directory, may not work on a build server, and is not team-friendly. The package has MSBuild targets that magically connects everything.

[Brent Kilboy]

Didn't work for me, so not as easy as you say it seems. Still gives the error on load and won't open the project after adding those lines to the csproj.

[Chris Martinez]

@BrentKilboy, you don't need to modify the project by hand unless you want to. I don't have enough context. If you have a Gist, repo, or some more context, I'm happy to elaborate. This is the official way to for it to be performed. It's also possible your build state is dirty. It might be worth clearing out bin and obj, then doing a project rebuild.

[CME64]

@ChrisMartinez really? the OP is clearly having a problem loading the project in the first place as well as most of who are coming here for the answer. so loading a nuget package into the project may not be the correct solution for the situation here.

[Chris Martinez]

@CME64 yes, really. The project doesn't load because the necessary .NET targeting pack was not found. The reference assemblies NuGet package includes all of the necessary files from the targeting pack and overrides the MSBuild properties and targets to use the NuGet file location instead of an installed location. I've expanded my answer with additional details, images, etc as well as a link to a working Gist.

[Basharat Hussain]

This worked for me, quite Easy

[Gxzzin]

Info that save lives! Thanks! :)