Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.

[festelo]

System.AggregateException: One or more errors occurred. (An error occurred while deserializing the Version property of class GoArcticApi.Models.Db.BaseCollectionObject: Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.)
 ---> System.FormatException: An error occurred while deserializing the Version property of class GoArcticApi.Models.Db.BaseCollectionObject: Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.
 ---> MongoDB.Bson.BsonSerializationException: Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.Serializers.SerializerBase`1.MongoDB.Bson.Serialization.IBsonSerializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize(IBsonSerializer serializer, BsonDeserializationContext context)
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)

[festelo]

This happened because of BackgroundService that tried to fetch db on start. After I put delay it works. But I think there should be a note in readme at least.

[kavatari]

@festelo I have the same issue here, could you explain what you mean by "delay"?

[kavatari]

Still looking for help with this issue. Found some interesting information, so the c# mongodb driver is not able to deserialize struct. DocumentVersion is a struct here.

[SRoddis]

Sorry for late response. I will have a look at it.

Thank you for the feedback.

Cheers, Sean

[Sacharkin]

Please fix this asp.

[samuelcadieux]

This issue is still happening, on our end we had a background service accessing Mongo too early. We've found that awaiting on IHostApplicationLifetime.ApplicationStarted.WaitHandle in our background service solves the concurrency issue.

[Lukejkw]

Any movement on this issue?

We are also getting it intermittently on .NET Core 6 application

[Lukejkw]

ning, on our end we had a background service accessing Mongo too early.

Are you able to elaborate on how you achieved this?

[samuelcadieux]

We're doing something like this:

using Microsoft.Extensions.Hosting;

internal static class WaitHandleExtensions
{
	public static Task WaitOneAsync(this WaitHandle waitHandle, CancellationToken ct)
		=> WaitOneAsync(waitHandle, TimeSpan.FromMilliseconds(-1), ct);

	public static Task WaitOneAsync(this WaitHandle waitHandle, TimeSpan timeout, CancellationToken ct)
	{
		var tcs = new TaskCompletionSource<bool>();
		var cancelRegistration = ct.Register(() => tcs.SetCanceled());
		var waitRegistration = ThreadPool.RegisterWaitForSingleObject(waitHandle, (_, _) => tcs.TrySetResult(true), null, timeout, true);

		var task = tcs.Task;
		task.ContinueWith(_ =>
		{
			waitRegistration.Unregister(null);
			cancelRegistration.Dispose();
		}, CancellationToken.None);

		return task;
	}
}

internal class EventConsumer : BackgroundService
{
	private readonly IHostApplicationLifetime m_hostLifetime;

	public EventConsumer(IHostApplicationLifetime hostLifetime)
	{
		m_hostLifetime = hostLifetime;
	}

	protected override async Task ExecuteAsync(CancellationToken ct = default)
	{
		// Waits for the migration service to be ready
		await m_hostLifetime.ApplicationStarted.WaitHandle.WaitOneAsync(ct)
			.ConfigureAwait(false);

		// ...
	}
}

[Lukejkw]

@SRoddis any ideas what is causing this issue? Happy to contribute with a fix if pointed in the right direction.

[Lukejkw]

We're doing something like this:

using Microsoft.Extensions.Hosting;

internal static class WaitHandleExtensions
{
	public static Task WaitOneAsync(this WaitHandle waitHandle, CancellationToken ct)
		=> WaitOneAsync(waitHandle, TimeSpan.FromMilliseconds(-1), ct);

	public static Task WaitOneAsync(this WaitHandle waitHandle, TimeSpan timeout, CancellationToken ct)
	{
		var tcs = new TaskCompletionSource<bool>();
		var cancelRegistration = ct.Register(() => tcs.SetCanceled());
		var waitRegistration = ThreadPool.RegisterWaitForSingleObject(waitHandle, (_, _) => tcs.TrySetResult(true), null, timeout, true);

		var task = tcs.Task;
		task.ContinueWith(_ =>
		{
			waitRegistration.Unregister(null);
			cancelRegistration.Dispose();
		}, CancellationToken.None);

		return task;
	}
}

internal class EventConsumer : BackgroundService
{
	private readonly IHostApplicationLifetime m_hostLifetime;

	public EventConsumer(IHostApplicationLifetime hostLifetime)
	{
		m_hostLifetime = hostLifetime;
	}

	protected override async Task ExecuteAsync(CancellationToken ct = default)
	{
		// Waits for the migration service to be ready
		await m_hostLifetime.ApplicationStarted.WaitHandle.WaitOneAsync(ct)
			.ConfigureAwait(false);

		// ...
	}
}

Thanks so much. The problem we've got is that we do not have direct control of the hosted service as it's a MassTransit service which coordinates the processing of messages off of queues.

There is no real way for us to tie into Mass Transit's lifecycle to delay the start up.

[char1es31]

System.AggregateException: One or more errors occurred. (An error occurred while deserializing the Version property of class GoArcticApi.Models.Db.BaseCollectionObject: Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.)
 ---> System.FormatException: An error occurred while deserializing the Version property of class GoArcticApi.Models.Db.BaseCollectionObject: Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.
 ---> MongoDB.Bson.BsonSerializationException: Value class Mongo.Migration.Documents.DocumentVersion cannot be deserialized.
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.Serializers.SerializerBase`1.MongoDB.Bson.Serialization.IBsonSerializer.Deserialize(BsonDeserializationContext context, BsonDeserializationArgs args)
   at MongoDB.Bson.Serialization.IBsonSerializerExtensions.Deserialize(IBsonSerializer serializer, BsonDeserializationContext context)
   at MongoDB.Bson.Serialization.BsonClassMapSerializer`1.DeserializeMemberValue(BsonDeserializationContext context, BsonMemberMap memberMap)

We had this issue when we were not calling MongoMigrationClient.Initialize(client);