Metadata step failed YamlDotNet.Core.YamlException: Type Microsoft.CodeAnalysis.CSharp.Symbols.ArrayTypeSymbol+SZArray is invisible

[jpelouse]

After making some changes to the documentation the docfx build step (version 1.6) failed with the following exception:

System.AggregateException: One or more errors occurred. ---> System.NullReferenceException: Object reference not set to an instance of an object.
 at Microsoft.DocAsCode.EntityModel.Plugins.BuildConceptualDocument.Build(FileModel model, IHostService host)
 at Microsoft.DocAsCode.EntityModel.Builders.DocumentBuilder.RunBuildSteps(IEnumerable`1 buildSteps, Action`1 action)
 at Microsoft.DocAsCode.EntityModel.Builders.DocumentBuilder.<>c__DisplayClass15_0.<BuildArticle>b__0(FileModel m)
 at Microsoft.DocAsCode.Plugins.DocumentExceptionExtensions.<>c__DisplayClass2_0`1.<RunAll>b__0(TElement s)
 at System.Threading.Tasks.Parallel.<>c__DisplayClass17_0`1.<ForWorker>b__1()
 at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask)
 at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object )
 --- End of inner exception stack trace ---
 at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
 at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
 at System.Threading.Tasks.Parallel.ForWorker[TLocal](Int32 fromInclusive, Int32 toExclusive, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Func`4 bodyWithLocal, Func`1 localInit, Action`1 localFinally)
 at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
 at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body)
 at Microsoft.DocAsCode.Plugins.DocumentExceptionExtensions.RunAll[TElement](IReadOnlyList`1 elements, Action`1 action, Int32 parallelism)
 at Microsoft.DocAsCode.EntityModel.Builders.DocumentBuilder.BuildCore(InnerBuildContext buildContext, DocumentBuildContext context)
 at Microsoft.DocAsCode.EntityModel.Builders.DocumentBuilder.Build(DocumentBuildParameters parameters)
 at Microsoft.DocAsCode.SubCommands.DocumentBuilderWrapper.BuildDocument(BuildJsonConfig config, TemplateManager templateManager, String baseDirectory, String outputDirectory, String pluginDirectory)
 at Microsoft.DocAsCode.SubCommands.BuildCommand.BuildDocument(String baseDirectory, String outputDirectory)
 at Microsoft.DocAsCode.SubCommands.BuildCommand.Exec(SubCommandRunningContext context)
 at Microsoft.DocAsCode.Program.ExecSubCommand(String[] args)
 ---> (Inner Exception #0) System.NullReferenceException: Object reference not set to an instance of an object.
 at Microsoft.DocAsCode.EntityModel.Plugins.BuildConceptualDocument.Build(FileModel model, IHostService host)
 at Microsoft.DocAsCode.EntityModel.Builders.DocumentBuilder.RunBuildSteps(IEnumerable`1 buildSteps, Action`1 action)
 at Microsoft.DocAsCode.EntityModel.Builders.DocumentBuilder.<>c__DisplayClass15_0.<BuildArticle>b__0(FileModel m)
 at Microsoft.DocAsCode.Plugins.DocumentExceptionExtensions.<>c__DisplayClass2_0`1.<RunAll>b__0(TElement s)
 at System.Threading.Tasks.Parallel.<>c__DisplayClass17_0`1.<ForWorker>b__1()
 at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask)
 at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object )<---

After updating to version 1.8 the following exception occurred within the metadata step. However, with the exception it is hard to figure out what is wrong.

System.AggregateException: One or more errors occurred. ---> Microsoft.DocAsCode.Exceptions.ExtractMetadataException: Error extracting metadata for {"Items":[...]} YamlDotNet.Core.YamlException: Type Microsoft.CodeAnalysis.CSharp.Symbols.ArrayTypeSymbol+SZArray is invisible.
    at Microsoft.DocAsCode.YamlSerialization.TypeInspectors.EmitTypeInspector.GetProperties(Type type, Object container)
    at YamlDotNet.Serialization.TypeInspectors.NamingConventionTypeInspector.GetProperties(Type type, Object container)
    at YamlDotNet.Serialization.YamlAttributesTypeInspector.GetProperties(Type type, Object container)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.YamlSerializer.EmitDocument(IEmitter emitter, IObjectDescriptor graph)
    at Microsoft.DocAsCode.Common.YamlUtility.Serialize(String path, Object graph)
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<GetMetadataFromProjectLevelCacheAsync>d__29`1.MoveNext()
 --- End of stack trace from previous location where exception was thrown ---
    at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<SaveAllMembersFromCacheAsync>d__25.MoveNext()
 --- End of stack trace from previous location where exception was thrown ---
    at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<ExtractMetadataAsync>d__15.MoveNext() ---> YamlDotNet.Core.YamlException: Type Microsoft.CodeAnalysis.CSharp.Symbols.ArrayTypeSymbol+SZArray is invisible.
    at Microsoft.DocAsCode.YamlSerialization.TypeInspectors.EmitTypeInspector.GetProperties(Type type, Object container)
    at YamlDotNet.Serialization.TypeInspectors.NamingConventionTypeInspector.GetProperties(Type type, Object container)
    at YamlDotNet.Serialization.YamlAttributesTypeInspector.GetProperties(Type type, Object container)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseList(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseProperties(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.ObjectGraphTraversalStrategies.FullObjectGraphTraversalStrategy.TraverseObject(IObjectDescriptor value, IObjectGraphVisitor visitor, Int32 currentDepth)
    at Microsoft.DocAsCode.YamlSerialization.YamlSerializer.EmitDocument(IEmitter emitter, IObjectDescriptor graph)
    at Microsoft.DocAsCode.Common.YamlUtility.Serialize(String path, Object graph)
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<GetMetadataFromProjectLevelCacheAsync>d__29`1.MoveNext()
 --- End of stack trace from previous location where exception was thrown ---
    at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<SaveAllMembersFromCacheAsync>d__25.MoveNext()
 --- End of stack trace from previous location where exception was thrown ---
    at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
    at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<ExtractMetadataAsync>d__15.MoveNext()
    --- End of inner exception stack trace ---
    at Microsoft.DocAsCode.Metadata.ManagedReference.ExtractMetadataWorker.<ExtractMetadataAsync>d__15.MoveNext()
    --- End of inner exception stack trace ---
    at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
    at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
    at Microsoft.DocAsCode.SubCommands.MetadataCommand.Exec(SubCommandRunningContext context)
    at Microsoft.DocAsCode.Program.ExecSubCommand(String[] args)

[vwxyzh]

@jpelouse I think this is a bug about attribute, is there some code like following in your project?

[Foo(typeof(Bar[]))]

[vwxyzh]

fixed in dev branch.

[jpelouse]

@vwxyzh We do not have attributes like [Foo(typeof(Bar[]))] within our project. However, we have array signs [] within comments like <see cref="Expression[]"/>. After removing such comments the meta-build finished successfully. Thank you for your help.