The collection has been marked as complete with regards to additions

[mikasoukhov]

Sometimes while using AsyncContext.Run I've got the following

System.InvalidOperationException
HResult=0x80131509
Message=The collection has been marked as complete with regards to additions.
Source=
StackTrace:

System.dll!System.Collections.Concurrent.BlockingCollection<System.Tuple<System.Threading.Tasks.Task, bool>>.TryAddWithNoTimeValidation(System.Tuple<System.Threading.Tasks.Task, bool> item, int millisecondsTimeout, System.Threading.CancellationToken cancellationToken) Unknown
Nito.AsyncEx.Context.dll!Nito.AsyncEx.AsyncContext.TaskQueue.TryAdd(System.Threading.Tasks.Task item, bool propagateExceptions) Unknown
Nito.AsyncEx.Context.dll!Nito.AsyncEx.AsyncContext.Enqueue(System.Threading.Tasks.Task task, bool propagateExceptions) Unknown
mscorlib.dll!System.Threading.Tasks.TaskContinuation.InlineIfPossibleOrElseQueue(System.Threading.Tasks.Task task, bool needsProtection) Unknown
mscorlib.dll!System.Threading.Tasks.Task.ContinueWithCore(System.Threading.Tasks.Task continuationTask, System.Threading.Tasks.TaskScheduler scheduler, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions options) Unknown
mscorlib.dll!System.Threading.Tasks.Task.ContinueWith(System.Action<System.Threading.Tasks.Task> continuationAction, System.Threading.Tasks.TaskScheduler scheduler, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, ref System.Threading.StackCrawlMark stackMark) Unknown
mscorlib.dll!System.Threading.Tasks.Task.ContinueWith(System.Action<System.Threading.Tasks.Task> continuationAction, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler) Unknown
Nito.AsyncEx.Context.dll!Nito.AsyncEx.AsyncContext.Enqueue(System.Threading.Tasks.Task task, bool propagateExceptions) Unknown
mscorlib.dll!System.Threading.Tasks.AwaitTaskContinuation.RunCallback(System.Threading.ContextCallback callback, object state, ref System.Threading.Tasks.Task currentTask) Unknown

In my case I use AsyncContext.Run for several methonds and the same time and I believe the error causes by following line

AsyncEx/src/Nito.AsyncEx.Context/AsyncContext.cs

Line 76 in 8a73d04

_queue.CompleteAdding();

Don't know why need to close underlying collection in case of empty tasks. Like my errors shows a newly may comes just a little bit later.

[StephenCleary]

Are you using fire-and-forget from within an AsyncContext.Run? Can you post sample code that reproduces this issue?