We are upgrading our project to .NET 6 from .NET Framework 4.5. We have a windows form application. Many of windows form commands has been depriciated in .NET 6. So to tackle this, I changed one of the Windows Forms project in the solution from:
<PropertyGroup>
<TargetFramework>net6.0-windows</TargetFramework>
</PropertyGroup>
to
<PropertyGroup>
<TargetFrameworks>net45;net6.0-windows</TargetFrameworks>
</PropertyGroup>
Now after changing this, I get the below error:
Project <another_project> targets 'net6.0-windows'. It cannot be referenced by a project that targets '.NETFramework,Version=v4.7.2'.
I understand why another_project is throwing this error message which is because the another_project is referenced in this Windows Form project and another_project's TargetFramework is .NET 6. So, I can change the TargetFramework for another_project to include .NET 4.5 as well.
But my question is, if I change this TargetFramework to TargetFrameworks and add multiple Framework there, does that mean my project is not upgrading to .NET 6 completely. Since it's using .net45 to complie/build in those cases, where it's failing to build in .NET 6. How does TargetFrameworks work??
I found the below link also, TargetFramework vs. TargetFrameworks (plural). But was not much helpful to understand this.
I'm assuming that you've upgraded your project files to SDK-style.
<TargetFrameworks>net45;net6.0-windows</TargetFrameworks> will effectively build your project twice - once for .NET 6.0 and once for .NET Framework 4.5.
(I'm not sure why your .NET Framework project is still targeting .NET 4.5 - I would have thought you should have retargeted it to 4.8 a long time ago...)
The output folders for these two targets will be:
For the DEBUG build:
\bin\Debug\net6.0-windows
\bin\Debug\net48
For the RELEASE build:
\bin\Release\net6.0-windows
\bin\Release\net48
Now if you want to reference one of those assemblies in another project, you're going to need to decide which to use, depending on the target framework for the dependent project.
In your case, it seems that you should be referencing the one in the "net6.0-windows" folder, so you should change your other project to reference that.
However, if you want the dependent project to ALSO be multi-targeted, you will need to change the hint path in the dependent project to use a compile variable to select the correct one.
For example, suppose your multi-targeted dependent project currently references a DLL using the following hint path:
<Reference Include="YourLibraryName">
path to referenced dll\bin\debug\net45\YourLibrary.dll
</Reference>
(Where "path to referenced dll" is whatever path is needed to locate the library.)
Clearly that will only reference the DEBUG Net 4.5 version of the library. You want it to reference the correct debug or release version and the correct .Net 4.5 or .Net 6.0 version. To do that, you can change the hint path to:
<path to referenced dll>\bin\$(Configuration)\$(TargetFramework)\YourLibrary.dll
At build time, $(Configuration) is replaced with the correct DEBUG or RELEASE string, depending on whether you're building DEBUG or RELEASE.
Similarly, the $(TargetFramework) will be replaced with the current build target, taken from the <TargetFrameworks>net45;net6.0-windows</TargetFrameworks> setting - either "net45" or "net6.0-windows".
Doing this will cause the correct DLL to be chosen from your multi-targeted project on which this project depends.
Note that this only applies to references using HintPath as above. If you're using project references, things would be different.
Also note that it's also possible (and maybe better) to create a NuGet package which will handle the dependencies etc properly, but that's a whole different story.
TargetFrameworks is used to build same project to multiple frameworks (so you have binary for each of them in output). It's usually used by libraries so they can be consumed by app targeted for different frameworks or, much less frequently, by apps, so they could be run on different machines.
I guess neither of theses is your cases. You just need to rework your app so it uses only features available in .NET Core.
Since you have added both net45 and net6.0-windows to your project it means that it should be compliable for both frameworks (i.e. it will be compiled twice, for each of the target frameworks), but you are trying to add reference to net6.0 project, which can't be used from net45. You need to either upgrade both to net6.0 only, or add net45 to the another_project.
Though usually it is another way around (compared to what you are trying to do), you use multitargeting for library projects (i.e. another_project in this case if I understand correctly) and keep one version for the executables (i.e. WinForms project should keep it's version).
Related
After consuming .net standard projects in a .net framework(4.6) console application, the dependencies of the .net standard projects are not copied into the output directory. This results in run time error of missing dlls. The "copy local" property is already true for the referenced projects. One possible solution is to add all the dependencies again in the console application, but is not a good idea. Is there a better solution to this?
After going through an article by Scott Hanselman, below solution worked like a charm.
"Using .NET Standard requires you to use PackageReference to eliminate the pain of “lots of packages” as well as properly handle transitive dependencies. While you may be able to use .NET Standard without PackageReference, I wouldn’t recommend it."
Add below line in the first "PropertyGroup" tag of the .net framework console application's ".csproj" file
<RestoreProjectStyle>PackageReference</RestoreProjectStyle>
There will not be any need to add again the .net standard projects' nuget dependencies in the console application.
Another answer is to publish the project:
dotnet publish -o path/to/output/folder
I cannot change the .NET version of my project. I installed .NET 4.8 via the Visual studio installer and manually downloaded it separately. Neither of these works.
I actually tried to change the framework in the .csproj project file
<TargetFramework> net5.0-windows </TargetFramework>
to
<TargetFramework>net48</TargetFramework>
and it doesn't work too...
I'm running out of solutions and don't really know what to do next.
If you're attempting to convert an SDK-style "net5.0-windows" project to a "net48" WinForms one you'll likely need to do more than just change TargetFramework.
Firstly, the Project node at the start of the ".csproj" file should look like this:
<Project Sdk="Microsoft.NET.Sdk.WindowsDesktop">
(A "net5.0" target doesn't need the .WindowsDesktop part of that.)
Secondly, you'll need to ensure that <UseWindowsForms>true</UseWindowsForms> is part of the main PropertyGroup.
Even after those changes you're still likely to get all sorts of issues if your project uses types that are not available in .net 4.8.
I understand this is quite a general question but I've not been able to find a reliable resource on solving the following scenario, nor it has been in one place. So I decided to ask here in the hopes to help others struggling with the same issue:
As a developer of .NET components I want to support a wide variety of .NET target frameworks. This topic had become quite important for me as of the recent explosion of target framework variants when dot net core and the dot net standard have been introduced.
So, imagine I am writing a C# library MyLib (that I would refer to as "product") which compiles to the MyLib.dll. I want to support the different range of target frameworks: net35, net40, net45, netstandard1.2 and etc. Therefore I create builds (MSBuild or csproj files) for each target framework and bundle them together in a single nuget package, respecting the nuget guidelines for the lib folder structure. Thus the product can be obtained from a single build artefact -- the nuget package.
For each target framework version I try to utilize its features and benefits and provide pollyfills for the lower versions or strip some features. In general the point is that the "product" is usable regardless of the consuming project's target framework -- I mean the nuget package for MyLib should install correctly, and the appropriate dll should be referenced.
So, a few questions arise:
Is it correct to share the same assembly version info across the different builds? Like re-using the same AssemblyInfo.cs file?
Which assembly attributes should not be shared between my builds? I have started another thread in regards to the [assembly: Guid("...")]] attribute. Other people are displaying concerns of the [assembly: AssemblyTitle("...")] attribute as well, while in a different context.
Is there any good or standardized approach of organizing a solution to support the described above build outcome. Do most projects out there really fend for themselves in achieving this?
My own way so far is to use a separate .csproj file per target framework for the same "product", but as the development progresses, it could become tedious to support multiple projects, even so as the target framework count is quite significant now.
Therefore I create builds (MSBuild or csproj files) for each target framework and bundle them together in a single nuget package.
If you are using the new csproj "SDK" format from Visual Studio 2017 then you don't even need to do that - it supports multiple target frameworks. For example:
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFrameworks>net451;netstandard1.3</TargetFrameworks>
</PropertyGroup>
</Project>
This project supports both the .NET Framework 4.5.1 and NETStandard1.3.
This automatically creates conditional compilation symbols so you can do things like #if NET451 or #if NETSTANDARD1_3 so you can conditionally apply code, if needed. You can likewise do this in the .csproj itself for including nuget packages for only one framework. The Dapper project has an example of this in their .csproj file.
Using the new dotnet cli, you can use dotnet pack to package it all up in to a nuget package.
I have a library written against .NET Standard 1.3 which should be compatible with the .NET Framework 4.6.1 runtime. The library uses the new csproj and works fine when referenced by .NET Core projects.
I also have a WPF project on a traditional csproj which should be able to use this library. In Visual Studio 2017 I managed to reference the .NET Standard library and it compiles without errors.
At runtime, it tries to load assemblies which are dependencies of the .NET Standard project and it fails with assembly not found exceptions. And I can see that my output folder doesn't have any of the dependencies indeed.
Is there a way to reference my library in such a way all the required dependencies are copied to the output folder (or an equivalent solution to make the WPF project run fine)?
Note: If I reference manually one by one all the missing dependencies and use runtime assembly version binding I can make it run, but I shouldn't really do this when referencing a project.
This is the full project page: https://github.com/UnoSD/PasswordManager
.NET Standard csproj
WPF package.config
WPF csproj
It currently is a Roslyn problem: GitHub issue
It is an active issue on Roslyn:
https://github.com/dotnet/roslyn/issues/17639
https://github.com/NuGet/Home/issues/4488
You have to specify compiler output for .NET 4.6.1
Put line like below into your csproj in your .NET Standard library project.
<TargetFrameworks>netstandard1.4;net461</TargetFrameworks>
(that should go instead <TargetFramework>netstandard1.4</TargetFramework>)
Build will produce binaries both for .NET 4.6.1 and .NET Core runtime compatible with NET Standard 1.4.
I have a .NET application that I built in 4.5, which has references to a bunch of libraries that were built in 4.5, which themselves have references to 4.5, etc. A user group that I'm trying to distribute the application to is having problems running the executable because they have 4.0 installed; in particular, they're getting a MissingMethodException:
Method not found: 'System.Type System.Runtime.InteropServices.Marshal.GetTypeFromCLSID(System.Guid)'.
Because we may have trouble getting each user upgraded to 4.5 (as none of them have admin permissions on their machines and this would require a separate upgrade request for each user), I'm looking at finding an easy way to rebuild the project as 4.0. This seems to require that I rebuild every library and its referenced libraries in 4.0; is there an easier way to do this than going through each library one by one and building a 4.0 version? I'm thinking maybe like a one-click option for "Rebuild all referenced libraries in target framework" or something like that.
If you have dependencies on .Net 4.5 DLLs then you will need to also get .Net 4.0 versions of those if you want to successfully downgrade your project. A .Net project can only reference .Net DLLs up to the same version of .Net as the referencing assembly.
The easiest way to do this is to use something like NuGet to manage your dependencies. Note that when you change the target framework version of your project in VS you will need to uninstall and re-install dependencies with NuGet as NuGet does not automatically do this for you when you change the target framework version.
Of course if all the dependencies are to your own code and you aren't publishing this through a dependency management system like NuGet you will need to downgrade all your other code to .Net 4.0 as well
When I use Visual Studio, I right click on the project, change the framework, fix the References and recompile. Usually straight forward.
Please, have a look at this MSDN page to correctly switch your project to a lower target framework without problems! It is a little bit outdated for what concerns versions, but the process is the same described!
This is based on my experience. I had an application initially created in .net framework 4.5 but I wanted to convert it in .net framework 4.0. I created new project initially created 4.0 and then I did copy and paste of all the forms and controls of my previous application and it works. Framework 4.5 is using Aero2 and 4.0 is Aero... Good Luck :)