[Bug] "Exception: The server disconnected unexpectedly." when running in Azure Devops

[BarkenBark]

Describe the bug
When running docfx to build my project documentation in Azure Devops, I get Exception: The server disconnected unexpectedly. followed by a stack trace (see log below). The exact command run is docfx docs/docfx.json --output 'D:\a\1\a\docs' --warningsAsErrors.

The docfx.json is the same as it has been previously successful runs. Will post a redacted version if needed.

The crash does not occur when running the same command locally on my machine, and I have not been able to reproduce is locally.

Log

+ docfx docs/docfx.json --output 'D:\a\1\a\docs' --warningsAsErrors
Loading project <REDACTED>
  Determining projects to restore...
  All projects are up-to-date for restore.
Exception: The server disconnected unexpectedly.
  at async Task<object> InvokeCoreAsync(int targetObject, string methodName,    
     List<object> parameters, Type expectedReturnType, CancellationToken        
     cancellationToken)                                                         
  at async Task<T> InvokeAsync<T>(int targetObject, string methodName,          
     List<object> parameters, CancellationToken cancellationToken)              
  at async Task<RemoteProjectFile> LoadProjectFileAsync(string projectFilePath, 
     string languageName, CancellationToken cancellationToken)                  
  at async Task<TResult> DoOperationAndReportProgressAsync<TResult>(            
     ProjectLoadOperation operation, string projectPath, string targetFramework,
     Func<Task<TResult>> doFunc)                                                
  at async Task<ImmutableArray<ProjectFileInfo>> LoadProjectFileInfosAsync(     
     CommandExecutor.cs:144                                                     
  at async Task<int> Execute(IConfiguration configuration, IEnumerable<string>  
     args) in CommandExecutor.cs:83                                             
  at async Task<int> RunAsync(IEnumerable<string> args) in CommandApp.cs:84  

To Reproduce
Steps to reproduce the behavior:

1. Run docfx in Azure Devops on VM Image windows-2022 (Version20240403.1.0)

Expected behavior
The docs should build succesfully.

Context (please complete the following information):

• OS: Azure Devops VM Image: windows-2022 (Version 20240403.1.0)
• Docfx version: 2.76

Additional context

• UPDATE: Downgrading to version 2.75.3 solves the issue for me.

[filzrev]

Exception: The server disconnected unexpectedly.

It seems to be thrown by following lines when calling MSBuildWorkspace::LoadProjectFileAsync.
https://github.com/dotnet/roslyn/blob/b67df4c5e39ac1a104b2e573542211d4d6b1cd1d/src/Workspaces/Core/MSBuild/Rpc/RpcClient.cs#L87-L89

docfx 2.76.0 using roslyn 4.9.2 packages. and out-of-process code analysis that are introduced in this version causing problems.
It might be resolved when next roslyn packages (v4.9.10) are released.
Related issue: dotnet/roslyn#72558

[thejonan]

Same problem here on a local project, after update from 2.75.3 to 2.76.0.

Here's the output:

Loading project /Users/jonan/Projects/SomeProject.csproj
  Determining projects to restore...
  All projects are up-to-date for restore.
Exception: The server disconnected unexpectedly.
  at async Task<object> InvokeCoreAsync(int targetObject, string methodName, List<object> parameters, Type
     expectedReturnType, CancellationToken cancellationToken)
  at async Task<T> InvokeAsync<T>(int targetObject, string methodName, List<object> parameters, CancellationToken
     cancellationToken)
  at async Task<RemoteProjectFile> LoadProjectFileAsync(string projectFilePath, string languageName, CancellationToken
     cancellationToken)
  at async Task<TResult> DoOperationAndReportProgressAsync<TResult>(ProjectLoadOperation operation, string projectPath,
     string targetFramework, Func<Task<TResult>> doFunc)
  at async Task<ImmutableArray<ProjectFileInfo>> LoadProjectFileInfosAsync(string projectPath, DiagnosticReportingOptions
     reportingOptions, CancellationToken cancellationToken)
  at async Task<ImmutableArray<ProjectInfo>> LoadProjectInfosFromPathAsync(string projectPath, DiagnosticReportingOptions
     reportingOptions, CancellationToken cancellationToken)
  at async Task<ImmutableArray<ProjectInfo>> LoadAsync(CancellationToken cancellationToken)
  at async Task<ImmutableArray<ProjectInfo>> LoadProjectInfoAsync(string projectFilePath, ProjectMap projectMap,
     IProgress<ProjectLoadProgress> progress, ILogger msbuildLogger, CancellationToken cancellationToken)
  at async Task<ImmutableArray<ProjectInfo>> LoadProjectInfoAsync(string projectFilePath, ProjectMap projectMap,
     IProgress<ProjectLoadProgress> progress, ILogger msbuildLogger, CancellationToken cancellationToken)
  at async Task<Project> OpenProjectAsync(string projectFilePath, ILogger msbuildLogger, IProgress<ProjectLoadProgress>
     progress, CancellationToken cancellationToken)
  at void MoveNext() in DotnetApiCatalog.Compile.cs:150
  at async (List<ValueTuple<IAssemblySymbol, Compilation>> symbol) Compile(ExtractMetadataConfig config, DotnetApiOptions
     options) in DotnetApiCatalog.Compile.cs:78
  at async Task <Exec>g__Build|5_0(ExtractMetadataConfig config, DotnetApiOptions options) in DotnetApiCatalog.cs:86
  at async Task Exec(MetadataJsonConfig config, DotnetApiOptions options, string configDirectory, string outputDirectory)
     in DotnetApiCatalog.cs:72
  at void <Execute>b__0() in DefaultCommand.cs:45
  at int Run(LogOptions options, Action run) in CommandHelper.cs:48
  at int Execute(CommandContext context, Options options) in DefaultCommand.cs:31
  at Task<int> Execute(CommandContext context, CommandSettings settings) in CommandOfT.cs:40
  at Task<int> Execute(CommandTree leaf, CommandTree tree, CommandContext context, ITypeResolver resolver, IConfiguration
     configuration) in CommandExecutor.cs:144
  at async Task<int> Execute(IConfiguration configuration, IEnumerable<string> args) in CommandExecutor.cs:83
  at async Task<int> RunAsync(IEnumerable<string> args) in CommandApp.cs:84

[filzrev]

Is it able to provide reproduceable files?

I've tried to reproduce problems with Azure Pipelines with following settings.
But I can't be able to reproduce.

azure-pipelines.yml

trigger:
- main

pool:
  vmImage: 'windows-2022'

steps:
- script: |
    dotnet tool install docfx -g
    pushd docs
    docfx metadata
    docfx build
    popd
  workingDirectory: "$(System.DefaultWorkingDirectory)"

[thejonan]

Here is the config file:

{
  "metadata": [{
    "src": [{
      "files": ["Core/Core.csproj"],
      "src": "../"
    }, {
      "files": ["Nodes/Nodes.csproj", "Execution/Execution.csproj"],
      "src": "../"
    }],
    "dest": "api",
    "filter": "docfx-filter-config.yml",
    "disableGitFeatures": true,
    "disableDefaultFilter": false
  }],
  "build": {
    "content": [{
      "files": ["**.yml", "**.md"],
      "exclude": "docfx-filter-config.yml"
    }],
    "resource": [{
      "files": ["images/**"]
    }],
    "overwrite": [{
      "files": ["**.md"],
      "exclude": [
        "obj/**",
        "bin/**",
        "_site/**"
      ]
    }],
    "dest": "../public",
    "_globalMetadata": {
      "_appTitle": "MyTest™",
      "_enableSearch": true
    },
    "globalMetadataFiles": [],
    "fileMetadataFiles": [],
    "template": ["default"],
    "postProcessors": [],
    "noLangKeyword": false,
    "keepFileLink": false,
    "cleanupCacheHistory": true,
    "disableGitFeatures": true,
    "force": true
  }
}

With the filter file being:

apiRules:
- include:
    uidRegex: ^Company\.Project\.Core.+
- exclude:
    uidRegex: _[^.]+$

I hope this would help.

[filzrev]

@thejonan
Is it able to provide following information additionaly?

• OS information that is used to run docfx command.
• Installed .NET SDK versions (dotnet --info command output)
• Target frameworks of *.csproj

As far as I've confirmed your configs.
It seems there is no problems. So it need to investigate .csproj contents or environment specific problems.

---

I've created sample project to load project file with roslyn API. (samples.zip)

Please try following steps.

1. Run docfx metadata command on docs directory. And confirm it' successfully completed.
2. Run dotnet run command on src directory. And confirm it's successfully completed.
3. If above two command successfully completed.
   Modfy src/Program.cs file to load "Core/Core.csproj" project and run dotnet run command.

[thejonan]

The crash occurs both on my Mac:

.NET SDK:
 Version:   7.0.313
 Commit:    7b4633fafd

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  14.4
 OS Platform: Darwin
 RID:         osx-arm64
 Base Path:   /usr/local/share/dotnet/sdk/7.0.313/

Host:
  Version:      7.0.16
  Architecture: arm64
  Commit:       567edafe61

.NET SDKs installed:
  6.0.414 [/usr/local/share/dotnet/sdk]
  6.0.415 [/usr/local/share/dotnet/sdk]
  6.0.416 [/usr/local/share/dotnet/sdk]
  6.0.419 [/usr/local/share/dotnet/sdk]
  7.0.308 [/usr/local/share/dotnet/sdk]
  7.0.309 [/usr/local/share/dotnet/sdk]
  7.0.310 [/usr/local/share/dotnet/sdk]
  7.0.313 [/usr/local/share/dotnet/sdk]

, and on a CI pipeline, based on docker's image: mcr.microsoft.com/dotnet/sdk:7.0 (digest: mcr.microsoft.com/dotnet/sdk@sha256:e44ea6d4cd019913b80726896e1127cd3fd6bd0f5c1d2074be02da3e54931127).

I'm targeting netstandard2.1 in my projects.

running docfx metadata in your docs folder results in:

Using .NET Core SDK 7.0.313
Loading project /Users/jonan/Downloads/samples/src/RoslynAnalysis.csproj
  Determining projects to restore...
/usr/local/share/dotnet/sdk/7.0.313/Sdks/Microsoft.NET.Sdk/targets/Microsoft.NET.TargetFrameworkInference.targets(151,5): error NETSDK1045: The current .NET SDK does not support targeting .NET 8.0.  Either target .NET 7.0 or lower, or use a version of the .NET SDK that supports .NET 8.0. [/Users/jonan/Downloads/samples/src/RoslynAnalysis.csproj]
error: /Users/jonan/Downloads/samples/src/obj/Release/net8.0/.NETCoreApp,Version=v8.0.AssemblyAttributes.cs(4,20): error
CS0400: The type or namespace name 'System' could not be found in the global namespace (are you missing an assembly
reference?)
...

which I guess is understood, given that I don't have net8 installed, but if I change your project's target to net7.0, then the result is:

Using .NET Core SDK 7.0.313
Loading project /Users/jonan/Downloads/samples/src/RoslynAnalysis.csproj
  Determining projects to restore...
  Restored /Users/jonan/Downloads/samples/src/RoslynAnalysis.csproj (in 6,12 sec).
__________________________________________________
Project "/Users/jonan/Downloads/samples/src/RoslynAnalysis.csproj" (Compile;CoreCompile target(s)):

/usr/local/share/dotnet/sdk/7.0.313/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(266,5): warning NETSDK1187: Package Microsoft.CodeAnalysis.Common 4.9.2 has a resource with the locale 'zh-Hans'. This locale has been normalized to the standard format 'zh-HANS' to prevent casing issues in the build. Consider notifying the package author about this casing issue.

...

warning: [Failure] Msbuild failed when processing the file '/Users/jonan/Downloads/samples/src/RoslynAnalysis.csproj' with
message: /usr/local/share/dotnet/sdk/7.0.313/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets:
(266, 5): Package Microsoft.CodeAnalysis.Workspaces.MSBuild 4.9.2 has a resource with the locale 'zh-Hant'. This locale
has been normalized to the standard format 'zh-HANT' to prevent casing issues in the build. Consider notifying the package
author about this casing issue.
Processing RoslynAnalysis
Creating output...


Build succeeded with warning.

    14 warning(s)
    0 error(s)

Very important aspect, as I've mentioned, is that with version 2.75.3 of the tool everything worked fine.

[filzrev]

@thejonan
Thanks for provide information and testing sample code.
It seems not able to reproduce problems by samples.

Very important aspect, as I've mentioned, is that with version 2.75.3 of the tool everything worked fine.

As noted above. It's expected to be caused by updating Roslyn packages to 4.9.2.
It change to API analysis operation in separated process.
And that cause The server disconnected unexpectedly. exception.

So if it is able to detect minimum reproducible code/environment, It helps to resolve problems.

[bradburyX]

Same problem here.

until this is fixed, the workaround is to simply downgrade, then everything works.
dotnet tool install docfx --version 2.75.0

would've been very helpful to provide this solution in the answers

[hexxone]

Bump.
Same Problem for me in a Gitlab CI docker build Pipeline.
After updating to v2.76.0 .
This is definetly a Regression from 2.75.3. There everything was and is still working.
Environment: .net6

Exact same exception:

#12 [build 6/6] RUN dotnet tool run docfx docs/docfx.json -o /app/docs
#12 1.781 Loading project /src/source/some.csproj
#12 2.595   Determining projects to restore...
#12 3.340   All projects are up-to-date for restore.
#12 3.927 Exception: The server disconnected unexpectedly.
#12 3.927   at async Task<object> InvokeCoreAsync(int targetObject, string methodName,    
#12 3.935      List<object> parameters, Type expectedReturnType, CancellationToken        
#12 3.935      cancellationToken)                                                         
#12 3.935   at async Task<T> InvokeAsync<T>(int targetObject, string methodName,          
#12 3.935      List<object> parameters, CancellationToken cancellationToken)              
#12 3.935   at async Task<RemoteProjectFile> LoadProjectFileAsync(string projectFilePath, 
#12 3.935      string languageName, CancellationToken cancellationToken)                  
#12 3.935   at async Task<TResult> DoOperationAndReportProgressAsync<TResult>(            
#12 3.935      ProjectLoadOperation operation, string projectPath, string targetFramework,
#12 3.935      Func<Task<TResult>> doFunc)                                                
#12 3.935   at async Task<ImmutableArray<ProjectFileInfo>> LoadProjectFileInfosAsync(     
#12 3.935      string projectPath, DiagnosticReportingOptions reportingOptions,           
#12 3.935      CancellationToken cancellationToken)                                       
#12 3.935   at async Task<ImmutableArray<ProjectInfo>> LoadProjectInfosFromPathAsync(     
#12 3.935      string projectPath, DiagnosticReportingOptions reportingOptions,           
#12 3.935      CancellationToken cancellationToken)  

[filzrev]

Some of the possible causes are when running docfx with .NET 6 or .NET 7.
And run build on .NET 8 SDK is not installed environment.

I've confirmed it's reproduced by using docker-based build on Windows.
And using .NET 6 or .NET 7 base image.

In this case, one of the following exceptions will occur.

• Exception: The server disconnected unexpectedly.
• System.IO.IOException: Broken pipe

Broken pipe IOException is reported as regression at dotnet/roslyn#71784.
And it seems not fixed yet.

[hexxone]

Broken pipe IOException is reported as regression at dotnet/roslyn#71784. And it seems not fixed yet.

Thanks for the investigating and info update. I have downgraded for now and will be looking forward to the fix then :)