core

.NET 7.0 Known Issues

You may encounter the following known issues, which may include workarounds, mitigations, or expected resolution timeframes.

.NET Runtime

Unable to evaluate expressions in a Blazor WebAssembly App

It isn’t possible to evaluate expressions in a Blazor WebAssembly app using .NET 7 RC1 https://github.com/dotnet/runtime/pull/75495

Workaround for a Blazor WebAssembly Hosted App

Copy the following into the server project (.csproj) of a .NET 7 Preview RC1 Blazor WebAssembly Hosted App:

 <ItemGroup>
  <PackageReference Include="Microsoft.CodeAnalysis.Scripting.Common" Version="3.7.0" ExcludeAssets="all" GeneratePathProperty="true"/>
  <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Scripting" Version="3.7.0" ExcludeAssets="all" GeneratePathProperty="true"/>
 </ItemGroup>
 <Target Name="_CopyCodeAnalysisDeps" AfterTargets="Build">
  <Copy SourceFiles="$(PkgMicrosoft_CodeAnalysis_Scripting_Common)\lib\netstandard2.0\Microsoft.CodeAnalysis.Scripting.dll"
              DestinationFolder="$(OutputPath)\BlazorDebugProxy"
              SkipUnchangedFiles="true"/>
  <Copy SourceFiles="$(PkgMicrosoft_CodeAnalysis_CSharp_Scripting)\lib\netstandard2.0\Microsoft.CodeAnalysis.CSharp.Scripting.dll"
     DestinationFolder="$(OutputPath)\BlazorDebugProxy"
     SkipUnchangedFiles="true"/>
 </Target>

Workaround for a Blazor WebAssembly Standalone App

Copy the following into a .NET 7 Preview RC1 Blazor WebAssembly project (.csproj):

 <ItemGroup>
  <PackageReference Include="Microsoft.CodeAnalysis.Scripting.Common" Version="3.7.0" ExcludeAssets="all" GeneratePathProperty="true"/>
  <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Scripting" Version="3.7.0" ExcludeAssets="all" GeneratePathProperty="true"/>
 </ItemGroup>
 <Target Name="_CopyCodeAnalysisDeps" AfterTargets="Build">
  <Copy SourceFiles="$(PkgMicrosoft_CodeAnalysis_Scripting_Common)\lib\netstandard2.0\Microsoft.CodeAnalysis.Scripting.dll"
              DestinationFolder="$(PkgMicrosoft_AspNetCore_Components_WebAssembly_DevServer)\tools\BlazorDebugProxy"
              SkipUnchangedFiles="true"/>
  <Copy SourceFiles="$(PkgMicrosoft_CodeAnalysis_CSharp_Scripting)\lib\netstandard2.0\Microsoft.CodeAnalysis.CSharp.Scripting.dll"
     DestinationFolder="$(PkgMicrosoft_AspNetCore_Components_WebAssembly_DevServer)\tools\BlazorDebugProxy"
     SkipUnchangedFiles="true"/>
 </Target>

That will copy the missing dependency into the DevServer package and enable evaluation of expression on Wasm debugging in .NET 7.0 Preview RC1 after a single build. This workaround only needs to be run once per package root to repair the DevServer package but should be harmless to leave in.

Unable to debug a Blazor WebAssembly App

It isn’t possible to debug a Blazor WebAssembly app using .NET 7 Preview 5 https://github.com/dotnet/runtime/pull/70383

Workaround for a Blazor WebAssembly Hosted App

Copy the following into the server project (.csproj) of a .NET 7 Preview 5 Blazor WebAssembly Hosted App:

    <ItemGroup>
        <PackageReference Include="Serilog.Extensions.Logging.File" Version="2.0.0" ExcludeAssets="all" GeneratePathProperty="true"/>
    </ItemGroup>
    <Target Name="_CopySerilogDeps" AfterTargets="Build">
        <Copy SourceFiles="$(PkgSerilog_Extensions_Logging_File)\lib\netstandard2.0\Serilog.Extensions.Logging.File.dll"
              DestinationFolder="$(OutputPath)\BlazorDebugProxy"
              SkipUnchangedFiles="true"/>
    </Target>

Workaround for a Blazor WebAssembly Standalone App

Copy the following into a .NET 7 Preview 5 Blazor WebAssembly project (.csproj):

    <ItemGroup>
        <PackageReference Include="Serilog.Extensions.Logging.File" Version="2.0.0" ExcludeAssets="all" GeneratePathProperty="true"/>
    </ItemGroup>
    <Target Name="_CopySerilogDeps" AfterTargets="Build">
        <Copy SourceFiles="$(PkgSerilog_Extensions_Logging_File)\lib\netstandard2.0\Serilog.Extensions.Logging.File.dll"
              DestinationFolder="$(PkgMicrosoft_AspNetCore_Components_WebAssembly_DevServer)\tools\BlazorDebugProxy"
              SkipUnchangedFiles="true"/>
    </Target>

That will copy the missing dependency into the DevServer package and enable Wasm debugging in .NET 7.0 Preview 5 after a single build. This workaround only needs to be run once per package root to repair the DevServer package but should be harmless to leave in as long as the project doesn’t have a different Serilog version requirement.

Assembly.GetType(“System.Net.Http.HttpClientHandler”, false, true) does not find some types but finds it when ignoreCase is set to false

When trying to do GetType with ignorecase as true in some cases does not find the type but finds it when ignoreCase is set to false. This only happens in .NET 7 preview 1 and doesn’t happen in .NET 6. More information and workaround can be found at https://github.com/dotnet/runtime/issues/65013.

Libraries have a non blocking issue in System.Security.Cryptography

.NET 7 Preview 3 on Linux skips revocation checks for expired certificates, reporting RevocationStatusUnknown when revocation checks were enabled. You can read more about this here: https://github.com/dotnet/runtime/issues/66803

Libraries have an unpredictable race condition in System.Security.Cryptography in Browser WASM

.NET 7 Preview 5 on Browser WASM has implemented the SHA1, SHA256, SHA384, SHA512 algorithms using the SubtleCrypto browser-native APIs. A race condition was discovered in System.Security.Cryptography’s implementation where the wrong hash value is returned unpredictably. You can read more about this here: https://github.com/dotnet/runtime/issues/69806. This only happens in .NET 7 Preview 5 and has been fixed in the latest code.

.NET SDK

[7.0] Projects using certain workloads don’t load, build, and or run if .NET 7 Preview SDK workloads are installed

If a preview .NET 7 SDK is installed, projects with workload dependencies such as microsoft.net.workload.mono.toolchain may fail to build, load, and or run. An example of this issue is described here.

Resolution

The best method to resolve the issue is to uninstall any .NET 7 preview SDKs. For detailed instructions, see dotnet uninstall instructions. For example, on Windows, dotnet preview SDKs can be uninstalled with add/remove programs. Another option is to try deleting the folder C:\Program Files\dotnet\sdk-manifests\7.0.100\microsoft.net.workload.mono.toolchain, but this will only work for file-based installs. Dotnet-core-uninstall is another option for uninstalling the .NET 7 preview SDKs.

[RC1] dotnet restore –interactive not working for authenticated feeds

The –interactive flag is not working with any dotnet.exe command in RC1. https://github.com/dotnet/sdk/issues/27597

Workarounds

dotnet user-jwts not functional in .NET 7 RC1

The dotnet user-jwts command line tool is not functional in .NET 7 RC1 due to an assembly resolution bug. When running the CLI, you will encounter the following exception.

$ dotnet user-jwts create
Could not load file or assembly 'Microsoft.Extensions.Configuration.Binder, Version=7.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified.

To circumvent this issue, you will need to modify the local installation to probe correctly for the Microsoft.Extensions.Configuration.Binder assembly

  1. Locate the user-jwts tool directory in your local SDK installation. This will typically be located in a path as follows:
  1. Locate the dotnet-user-jwts.deps.json file and make the following modifications:
{
    "targets": {
        ".NETCoreApp,Version=v7.0": {
            "dotnet-user-jwts/7.0.0-rc.1.22426.10": {
            "dependencies": {
+               "Microsoft.Extensions.Configuration.Binder": "7.0.0-rc.1.22426.10"
            },
+           "Microsoft.Extensions.Configuration.Binder/7.0.0-rc.1.22426.10": {
+               "dependencies": {
+                   "Microsoft.Extensions.Configuration.Abstractions": "7.0.0-rc.1.22426.10"
+               },
+               "runtime": {
+                   "lib/net7.0/Microsoft.Extensions.Configuration.Binder.dll": {
+                       "assemblyVersion": "7.0.0.0",
+                       "fileVersion": "7.0.22.42610"
+               }
+           }
        },
    },
    "libraries": {
+       "Microsoft.Extensions.Configuration.Binder/7.0.0-rc.1.22426.10": {
+           "type": "package",
+           "serviceable": true,
+           "sha512": "",
+           "path": "microsoft.extensions.configuration.binder/7.0.0-rc.1.22426.10",
+           "hashPath": "microsoft.extensions.configuration.binder.7.0.0-rc.1.22426.10.nupkg.sha512"
+       },
    }
}
  1. Locate the Microsoft.Extensions.Configuration.Binder assembly in the directory associated with the Microsoft.AspNetCore.App shared runtime. This will typically be located in a path as follows:
  1. Copy the assembly from Step 3 to the user-jwts tool directory from Step 1.
  1. Note that the install directory for the SDK may not be deleted during uninstall due to applying this workaround, e.g. when updating to 7.0.0-rc.2. If that occurs, delete the directory manually.

This issue will be resolved in .NET 7 RC 2.

.NET MSBuild

.NET MSBuild 17.5 previews shipped with public classes for the new console logger

.NET MSBuild is adding a new live console logger in a future release. The initial implementation that shipped in 17.5 previews (and will ship in .NET SDK 7.0.200) had the classes public. This new logger is still in preview and not meant for public consumption of the classes or apis. 17.5.0 will ship with the classes marked internal and that change will release in the .NET SDK 7.0.201 release in March.

The logger will also be renamed for 17.6. https://github.com/dotnet/msbuild/pull/8343

[7.0.200] Using the --output option fails for many commands when targeting a solution

A breaking change was introduced that was intended to prevent common build errors. However, many users relied on this behavior to build their projects. We have downgraded this change to a warning and are intent on releasing this fix in 7.0.201. Please see the linked breaking change notification for more details.

ASP.NET Core

[7.0] bind get, set, after can’t be used in 7.0 Blazor applications

In .NET 7 Preview 7, we’ve introduced a new feature for binding values to components using the new bind:get, bind:set and bind:after syntax. As part of a follow-up work to address some issues we’ve learned about related to that feature, we had to take a two-part fix both in dotnet/aspnetcore and dotnet/razor-compiler repos. Unfortunately, we had an issue with our dependency update process and the razor compiler changes did not make it into the 7.0 build. As a result, when you try to use bind, get, set, after on 7.0 Blazor application, the compiler will emit code against non existing APIs and users will be presented with an error like Can't convert from EventCallback<T> to Func<T,Task>. An update for the compiler is planned as part of the 7.0.1 release that will update the compiler to target the new APIs and make this feature work as expected from them on.

Users that are not relying on bind get, set, after will not be affected by this issue.

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