having spent the better part of two days on this, time to get some help.
I am reworking our CI build, and have a VS2017 solution which was on .net 4.6.1, using packages.config style nuget refs, and TeamCity was using the NuGet runner v3.4.4 to restore the packages. It was originally build probably using VS2008 or 10, then converted to 2017 in 2018. Someone checked in the packages directory and it's been that way for years.
Time to bring it up to more modern standards. I converted the projects to use packageReference, and now am using msbuild and the restore;build target to restore my packages and build the solution. Works well EXCEPT for this one package.
Even in VisualStudio 2017 15.8.7, the build (which does the restore of course) is failing to restore the smtp-impostor package using a packageReference with the following error:
NU1202: Package smtp-impostor 2.0.8 is not compatible with net461 (.NETFramework,Version=v4.0). Package smtp-impostor 2.0.8 supports: netframework40 (.NetFramework 4.0,Version=v0.0)
I can't get Google to find a single useful post when searching for "netframework40".
If I use nuget3.4.4 CLI, it works fine (it seems to call msbuild 4.0). If I use nuget 5.6 CLI, I get the error message; it's using the msbuild that comes with Visual Studio 2017.
I see a lot of posts on how to get nuget to use a different version of msbuild, but I don't see how to tell msbuild to use an earlier version of nuget!
I have tried:
retargeting the solution to v4.0 - same error occurs - first part of error just changes to net40
setting the ToolsVersion in the csproj file tag to 14.0
Setting the PlatformToolsVersion property in the csproj file to 14.0.
No dice.
I really don't want to stay with packages.config for this project (and an extra CI build step) nor checkin the single DLL for the package into my repo. It's looking more like I'll jsut have to scrap the packageReference upgrade and stick with the old style nuget runner package restore.
Anyone ever seen this? Any ideas where "netframework40" comes from and why newer nuget can't match it with net40?
Thank you in Advance!
Newer versions of NuGet.exe can't resolve framework match when
restoring older packages (net40, netframework40)
The issue is that this nuget package smtp-impostor 2.0.8 is not compatible with the new PackageReference format and has nothing to do with Nuget V3.4.4 or Nuget V5.6.x.
Actually, the package was published on 2011 and the new package management format PackageReference was used since VS2017.
Besides, the author did not make any changes to the package to accommodate the new Packagereference. And I faced the same issue in my side.
Suggestion
As a workaround, you have to use packages.config to install this nuget package rather than PackageReference.
Since VS2017, VS adds the new PackageReference nuget management format and for your old VS2008, it uses Packages.config.
Or you could contains the author of the nuget package to change it.
Two of my vscode C# aspnetcore projects are showing different versions of a third party model and I have manually changed the .csproj to point to the correct nuget package version. I have run the following commands:
nuget locals all -clear
nuget restore
Yet when I Go To Definition on the model, it's still showing the older version. What gives?
Apparently you have to close and reopen VS Code before you see updated nuget code when viewing definitions (F12). So frustrating.
After downloading Virto Commerce source and compiling in Visual Studio all went smoothly. After updating NUGET Packages, I get compile errors. Please see graphic.
Compile errors
In your case, you have updated Netonsoft.Json and it cause obsolete method compilation error.
You should avoid updating nuget packages yourself, this should be done by the platform team.
I've applied only Minor Updates and all works as expected.
So, I recommend to install major updates of NUGET packages carefuller.
I've installed the newly released version of Visual Studio 2017 and started a fresh ASP.NET Core project targeting .NET Core.
Out of the box, I'm getting the
The type or namespace name 'System' could not be found (are you
missing a using directive or an assembly reference?)
error. Any idea what's causing this and how to fix it?
Also, looks like there are problems with NuGet packages as well:
I also tried dotnet restore on the project through the command line and got the following error:
P.S. Kind of disheartening that you get an error in a fresh new project in the latest version of Visual Studio 2017!
UPDATE:
SDK version is v 1.0.1 -- see below:
UPDATE 2:
This is very strange. Looks like the original problem was due to NuGet package source pointing to a folder under Visual Studio 2015 folder. I unchecked it and left only nuget.org. With that my project seemed to have restored all the packages and when I started the project it loads up the standard ASP.NET page. But if I open startup.cs file, I get red squigglies all over the place but if I run the project, it works fine. What's going on here?
UPDATE 3:
I closed the project and VS 2017. I then restarted VS 2017 and opened the project and now it seems to be fine. And I'm not referencing the .NETStandard library 1.6.1 and everything seems to be working fine now.
I had the same issue in my Visual studio 2017 .Net Core application. I closed the Visual studio and re-open fixed everything.
Came across the same issue today. I had an old nuget source that no longer existed. So I went into Tools > Nuget Packet Manager and un-checked the wrong one. Hit "Ok", and then rebuilt the project, and it works great now. It seems like you stumbled onto it, but also wanted to verify that it fixed my issue, and it does.
I had the same problem, first when converting a VS2015 net core mvc web project to 2017 and then when trying to create a new core web application in 2017.
Went to Tools|NuGet Package Manager|Package Manager Settings - checked 'Allow NuGet to download missing packages' and 'Automatically check for missing packages during build in VS' and then clicked 'Clear All NuGet Cache(s)'.
Then re-built the solution - it found and loaded all the required packages and ran OK.
May not work for all cases but simple and worth a try.
Multiple closing and reopening of VS2017 fixed it for me.
I had the same issue, the solution for me was to clear the NuGet cache. Tools > NuGet Package Manager > Package Manager Settings > Clear All NuGet Cache(s)
Check the version .NET Command Line Tools in CMD, just type dotnet --info. If version is 1.0.0, then try to install latest version .NET Core SDK from here.
Find the broken project and right click, Unload, right click, Re-load. Fastest fix for me.
If you get the problem while using the CLI, try doing nuget restore instead of dotnet restore as that sometimes pulls down packages that the dotnet CLI seems to miss.
I have had the same issue with Visual Studio 2019 and .NET Core SDK 2.2.
These steps solved the problem:
Close the Visual Studio
Open the Visual Studio as Administrator
Open the Solution
Right click on Solution -> Restore NuGet Packages
I've tried all answers above. For me works only removal and adding the reference again described in the following steps:
Open 'References' under the project.
Right click on 'System' reference.
Click on 'Remove'.
Right click on 'References'.
Click 'Add Reference...'.
From right menu choose an 'Assemblies',
In a search field type 'System'.
Choose 'System' from the list.
Click 'Add' button.
IMPORTANT: Restart the Visual Studio.
'System' reference you can replace with any you need.
Try adding the following line above the other references in the csproj file
<Reference Include="netstandard" />
For me the problem was caused by my project having a custom IntermediateOutputPath. For some reason, if project_name.csproj.nuget.g.targets is not in obj subfolder of project folder, the error occurs.
Using default IntermediateOutputPath or keeping a shadow copy of project_name.csproj.nuget.g.targets in fake obj folder solves the problem for me.
This issue seems to be triggered by a myriad of reasons. Mine was caused by cloning directly from VSTS using Git Bash, my project directory had spaces in it. Git Bash changed those spaces in the path to %20. It was throwing off all the references in my project. So for anyone who tried everything else and are at their wits end, make sure %20 is not in the path.
So, I have cloned the repository from github and started getting this error.
It was my project uploaded from another machine. I later realized that I have used the materialdesign packages in my project.
I have uninstalled and reinstalled these packages and it fixed my issue.
Had the same problem. Uninstalled Application Insights from my projects using the nuget package manager. I'm not looking at that yet, I just wanted core and unit tests. Problem solved.
I also had the same problem.
The is no SDK folder under the Dependencies one. Therefore, no Microsoft.NetCore.App libraries !
To solve this problem, in Nuget manager window, install any nuget which depends on .NetCoreApp (you can install for example Microsoft.AspNetCore or BundlerMinifier.Core from the Microsoft Visual Studio Offline Packages source).
The SDK will be restored by the same time.
Once it is back, you can uninstall the previously added nuget. The SDK will remain in place.
Not quite sure in which order vs 2017 trying to resolve packages.
But my situation was following. In my VS2015 I had configured local and 3rd party source for nuget packages, newly installed version of 2017 loaded them too.
https://api.nuget.org/v3/index.json was first in list.
But vs2017 throwed an error that it can't restore .net core libraries from my another local repo.
After I unchecked all of them except https://api.nuget.org/v3/index.json, it had started to working normally.
I had this problem too, but not right now, this steps solved my problem: Choose Project -> Properties from the menu bar. In the Project properties window, under Configuration Properties -> General, make sure that Common Language Runtime Support is set to Common Language Runtime Support (/clr)
Simply opening the NuGet package manager and then the Visual Studio settings related to it - without changing anything - merely looking around, and when I closed out, the problem was gone.
This seems to be an intermittent issue that can come and go for no obvious reason.
None of the answers here worked for me so I'm posting what did work.
My errors were mostly the same as the original poster but I also had:
Error loading meta data for 'Microsoft.Extensions.FileProviders.Embedded.2.0.1'
hexadecimal value 0x1C invalid character
Every time I attempted to download a different nuget package or restore old packages I would see this error. I also saw the other errors such as:
type or namespace system could not be found
What worked for me:
opened the filepath that the error said the bad metadata was in, which for me was C:\Program Files\dotnet\sdk\NuGetFallbackFolder\microsoft.extensions.fileproviders.embedded\2.0.1
Then, I put the contents of that folder into another folder I named "hiding".
Then, I went back to the nuget package manager and tried to install a package, hoping to have the SDK restored. IOt worked successfully, and all my other errors were gone as well, and the fresh new project runs as it should!
The problem for me occurred when running my Visual Studio as Admin with a separate user-- I had created a Git Repo with the source files in the user documents of my normal account. When I created a new solution in that folder the above errors occurred. Try creating your project in a different place and see if the error still occurs.
I was facing the same issue when I created a new project (.net Core 2.2) in VS2019.In my case there was an Azure package which was creating the problem.I uninstalled it and the project started working fine.
Run mentioned below command to uninstall the package.
Uninstall-Package Microsoft.VisualStudio.Azure.Containers.Tools.Targets -Version 1.7.10
I had the same problem. I cloned a github project and this error came. So I deleted the cloned project and then I cloned the project again and it worked fine.
I haven't had problems with nuget until now, i created a blank a UWP project and decided to add some few nuget packages to it and it keeps saying 'Package restore failed. Rolling back package changes for App1'. But when i do this a WPF project it successfully install. Does anyone here knows why this is happening or is also ?
I ran into the same problem with other packages. The problem is that many NuGet packages don't seem to be compatible with UWP. This incompatibility info is shown in the output console rather than the error console of Visual Studio.
See also .NETcore, UWP - can't install NuGet package.