ValueTask<TResult> documentation is outdated for .NET 10 - repeated await no longer throws

[AnastasiaGolomazova]

Type of issue

Typo

Description

The documentation for ValueTask on learn.microsoft.com states:

"A ValueTask instance may only be awaited once, and consumers may not read Result until the instance has completed."

In .NET 10.0.300 (release), this is no longer true. I tested the following scenarios and none of them threw an exception:

Awaiting the same ValueTask instance multiple times

Calling .AsTask() multiple times

Accessing .Result before the task completed

Calling .Preserve() after .AsTask()

The documentation should be updated to reflect the actual behavior in .NET 10

Example:

Expected behavior (per docs): The second await should throw InvalidOperationException.

Actual behavior (.NET 10.0.300): Both await calls succeed and print the same result.

Environment:

.NET 10.0.300

Windows x64

Console application targeting net10.0

Page URL

https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.valuetask?view=net-10.0

Content source URL

https://github.com/dotnet/dotnet-api-docs-temp/blob/live/xml/System.Threading.Tasks/ValueTask.xml

Document Version Independent Id

8146b64b-4225-5572-23b2-c959597dfb55

Platform Id

5c4fec22-5232-0ebf-2ed8-a486d802cf53

Article author

@dotnet-bot

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-threading-tasks

[AnastasiaGolomazova]

Am I crazy and not noticing something?

[AnastasiaGolomazova]

Attaching the code, but I have used other tests to cause the error, but it has not succeeded.

var service = new CatService();

var task = service.GetCatAsync(1);
var res = await task;
Console.WriteLine(res);
var res2 = await task;
Console.WriteLine(res2);

public class CatService
{
    private readonly Dictionary<int, string> _catCache = new();

    public ValueTask<string> GetCatAsync(int id)
    {
        if (_catCache.TryGetValue(id, out var name))
        {
            return new ValueTask<string>( name);
        }

        return FetchCatFromDatabaseAsync(id);
    }

    private async ValueTask<string> FetchCatFromDatabaseAsync(int id)
    {
        await Task.Delay(100);
        return $"Cat ID {id}";
    }
}