core

.NET Core 3.1 Known Issues

This document lists known issues for .NET Core 3.1 Preview 1 and beyond releases which may be encountered during usage.

.NET Core

.NET Core 3.1.26

Users/Developers may see missing template for Winforms Control library in Visual Studio (16.11) with latest servicing update. Users may also see following error when trying to create Winforms Control library via command line interface (CLI) command dotnet -new winformslib.

Error reading template from file: /WinFormsLibrary-CSharp/.template.config/template.json | Error = After parsing a value an unexpected character was encountered: “. Path ‘symbols.Framework.choices[0].description’, line 34, position 10. No templates found matching: ‘winformslib’.

As a workaround, users can install .NET 3.1 SDK online to unblock themselves. However, this may mislead users that they are creating out of support “.NET core 3.0 “ application as shown in below picture but the actual application created is targeting .NET 3.1.

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.NET Core 3.1.20

Between the time of 10/12/2021 10:00AM PST and 10/14/2021 10:00AM PST the .NET Core 3.1.20 update was available as an automatic update on Microsoft Update to operating systems Windows Server 2012 R2, Windows Server 2016, Windows Server version 1709, Windows Server version 1803, Windows Server 2019, Windows Server version 1903, Windows Server version 1909, Windows Server version 2004, and Windows Server version 20H2 for the x64 architecture. Systems that are configured to take automatic updates from Microsoft Update with these operating systems and with any of the .NET Core versions 3.1.10 through 3.1.19 installed may have been updated to 3.1.20 during this time. The .NET Core 3.1.20 is no longer available as an automatic update, but will continue to be available through Microsoft Update WSUS and Microsoft Catalog.

.NET Core 3.1.2

When a .NET Core application uses both System.Data.SqlClient and a .NETFramework library which requires System.Data, the .NET Core 3.1.2 runtime can cause the application to fail with an exception like the following:

System.IO.FileLoadException: Could not load file or assembly 'System.Data.SqlClient, Version=4.6.1.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The located assembly's manifest definition does not match the assembly reference. <br/>
System.IO.FileNotFoundException: Could not load file or assembly 'System.Data.SqlClient, Version=4.6.1.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The system cannot find the file specified.

To fix this, update the application to use the System.Data.SqlClient package version 4.8.1.

.NET Core 3.1.2 SDK (3.1.102 SDK)

Packages built out of dotnet/corefx but part of the “Microsoft.AspNetCore.App” Shared Framework don’t exist in the targeting pack for 3.1.2. Due to this, after upgrading to 3.1.2, apps which were able to compile against some assemblies can no longer compile. This will have an impact on both .NET Core as well as ASP.NET Core.

List of affected assemblies

Current workaround for this issue is to add an explicit PackageReference to the packages corresponding to above mentioned assemblies. You can find more information about this issue on dotnet/aspnetcore A fix for this will be available in a future servicing release of 3.1.X.

.NET Core 3.1.1 SDK (3.1.101 SDK)

.NET Core 3.1.0 SDK (3.1.100 SDK)

.NET Core installation on macOS Catalina (10.15)

macOS Catalina introduced new security features which affect the .NET Core installers. If you run the installer after downloading using a web browser, a warning dialog will open stating the package "...can't be opened because Apple cannot check it for malicious software.", and the installation will be stopped.

To override this behavior, go to Settings : Security & Privacy and choose “Open Anyway” next to the dotnet installer text.

We are working to update our installers for the new Catalina requirements. These will be released during an upcoming monthly update.

.NET Core 3.1 SDK, all releases

ASP.NET Core

3.1.0

This is a cosmetic bug: the hosting bundle is expected to function normally.

This is fixed with 3.1.1. More information at dotnet/core#3962.

The Hosting Bundle briefly shows that it is installing “Microsoft .NET Core Runtime - 3.1.0 Preview 3”. That string is also visible in Add/Remove Programs after the install completes. This is not the old November 2019 3.1.0 Preview 3 Runtime. The Hosting Bundle is installing a more recent build of 3.1.0 that has incorrect branding.

To fix this, repair the .NET Core Runtime installation. (Execute the installer again and click Repair, or find the .NET Core Runtime 3.1.0 installation in Add/Remove Programs, select Modify, then click Repair.)

This is fixed with 3.1.1. More information at dotnet/core#3962 and dotnet/runtime#703.

Missing this file can cause errors like the following, for example when running dotnet --info:

A fatal error was encountered. The library ‘hostpolicy.dll’ required to execute the application was not found in ‘C:\Program Files\dotnet\shared\Microsoft.NETCore.App\3.1.0’.

Preview1

Due to an package authoring error, the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation is missing build targets that are required to for runtime compilation to work. Users of this package will see errors along the lines of "System.InvalidOperationException: Cannot find reference assembly '...' file for package '...'*

To resolve this issue, add the following contents to the your project file:

  <PropertyGroup>
    <PreserveCompilationContext>true</PreserveCompilationContext>
    <PreserveCompilationReferences>true</PreserveCompilationReferences>
    <GenerateRazorHostingAssemblyInfo>true</GenerateRazorHostingAssemblyInfo>
    <RazorUpToDateReloadFileTypes>$(RazorUpToDateReloadFileTypes.Replace('.cshtml', ''))</RazorUpToDateReloadFileTypes>
    <AddCshtmlFilesToDotNetWatchList>false</AddCshtmlFilesToDotNetWatchList>
  </PropertyGroup>

This issue has been resolved in 3.1 Preview 2.

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