How do I reference a .NET standard 2.0 NuGet package correctly in winforms .NET framework 4.8 project?

Question

0.00/5 (No votes)

See more:

Hello everyone,

I had a .Net Standard 2.1 library that I tried to reference in a .Net Framework 4.8 WinForms application, which I discovered that does not work because .Net Standard 2.1 and .Net Framework 4.8 are not compatible..

So, I changed the class library to reference .Net Standard 2.0 and re-built and took the release dll file to the winforms application,

But I got the following exception:

Quote:
System.IO.FileNotFoundException: 'Could not load file or assembly 'netstandard, Version=2.1.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. The system cannot find the file specified.'
Inner Exception:
FileNotFoundException: Could not load file or assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51' or one of its dependencies. The system cannot find the file specified.

I made a Nuget package from the .Net standard class library, and used it in another WPF project (.Net Framework 4.8) and it worked fine,

I used it in a new winforms project (.Net Framework 4.8) and it worked fine,

I removed the reference for the .dll file from the original winforms project and used the nuget package instead, but got the same exception..

So my guess is that using the .Net Standard 2.1 reference first has somehow corrupted the project, so when trying to use the .Net Standard 2.0 nuget package I get the exception despite not having a reference to .Net Standard 2.1

So how can I find where is the .Net Standard 2.1 reference?
and how can I solve this exception?

What I have tried:

1. Unloaded the project and examined the vbproj file searching for a .Net Standard 2.1 reference, didn't find any..

2. Out of desperation, I searched the entire project for "2.1" hoping to find where is that reference, but with no avail.

3. Googled, the issue is not a problem with .Net Standard, it's about this specific situation, I just don't know how to investigate further.

4. Git reset -- hard to the commit before adding the 2.1 version, then added the 2.0 version.. still got the same exception..

Posted 21-Aug-20 18:30pm

Ahmad_kelany

Updated 14-Jun-22 16:30pm

v2

Add a Solution

Comments

Sandeep Mewara 22-Aug-20 2:03am

1. Deleted the bin & obj folders?
2. Deleted old 2.1 nuget downloaded that could be sitting on your system?

Ahmad_kelany 22-Aug-20 2:37am

1. yes, I did.. same exception.

2. 2.1 was a .dll file not a nuget, the nuget package is 2.0 from the start, and I deleted that .dll file.

[no name] 22-Aug-20 10:53am

Try it with a new "minimal" Windows Forms VS project.

WPF, Windows Forms, UWP, the various Frameworks, are all "works in progress"; and not always / ever in sync.

(And the reason one uses the latest release of everything is because one wants those features, not just "because"; if you want stability)

Ahmad_kelany 22-Aug-20 17:16pm

I tried it with a complete WPF project, and with a new Winforms project, and it worked fine in both cases, as I stated in the question,

As I said, probably the problem is not in the frameworks, but in the project's specific situation,

And I totally agree with your last line, I used 2.1 standard for a certain feature, but as it was incompatible with 4.8 framework, I foregone that feature and went back to 2.0..

My main question is how to investigate that exception and what causes it..

[no name] 23-Aug-20 12:41pm

The issue seems to be you trying to use a "Nuget package" (for your dll) instead of simply referencing your dll. It would seem you need to look at similar Nuget packages and figure out why yours doesn't work.

Ahmad_kelany 23-Aug-20 18:14pm

Sir,

In the third line of my question I said that I referenced the .dll file produced by the 2.0 standard, and I still got the exception,

Me trying to use Nuegt package was just trying another approach to avoid the exception, not using it "just because" ..

And the .dll file and the Nuget package work fine in other projects, be it WPF or winForms,

So clearly the issue is not in the .dll file or in the Nuget Package,

As I said, there is an issue in the project situation, and I'am trying to figure it out, why does it give me that exception despite the package referencing 2.0 standard not 2.1?

Notice that the exception says that it couldn't find 2.1 standard, but the inner exception says it can't find 2.0 standard..
Verily it seems that I am missing something, but I still don't know what? or how to investigate further.. 😅

[no name] 23-Aug-20 22:35pm

What you think you said and what you said are 2 different things: "I tried it with a complete WPF project, and with a new Winforms project, and it worked fine in both cases"

Your "problem" is that you're intent on salvaging a corrupt project when you could just copy your components into one that works (as you've "said" above).

I'm using a .NET Standard 2.0 dll with Core 3.0, Framework 4.7, WPF, and UWP store apps. No problem. No Windows Forms. No Nuget.

Florian2C 2-Sep-20 23:59pm

I have the same issue and do not find a solution after hours of research.

Did you find any fix?

Florian2C 3-Sep-20 12:56pm

The only way I found now, is to create a new project an import all forms into it.

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Maciej Los · Answer 1 · 2020-09-02T21:35:00

I'd suggest to read this: Troubleshoot broken references - Visual Studio | Microsoft Docs[^] and this: Manage references in a project - Visual Studio | Microsoft Docs[^] and this: Understanding Clean, Build and Rebuild in Visual Studio[^]

These may be helpful too:
Removing all unused references from a project in Visual Studio projects - Stack Overflow[^]
How do I find files that are missing from visual studio projects? - Stack Overflow[^]

I'd inspect solution/project file for missing reference(s).

Member 14988897 · Answer 2 · 2020-11-09T23:26:00

You need to check the compatibility table for net core , net framework and net standard frameworks. for instance application targeting net core 3.0 has backward compatibility for net framework 2.0 and lower, so if you include a package version more then 2.1 in app targeting 3.0 you will get this issue

compatibility check can be done on MSN website.

In such an environment, code sharing becomes a major challenge. You need to understand where APIs are available and make sure that shared components only use APIs that are available across all .NET implementations you’re using

How do I reference a .NET standard 2.0 NuGet package correctly in winforms .NET framework 4.8 project?

2 solutions

Solution 2

Solution 3

Add your solution here

Preview 0