SignalR + Redis backplane = System.InvalidOperationException: queue full

I am using SignalR with redis backplane. To set it up I am using simple code

var redisConfig = new RedisScaleoutConfiguration("connectionString","eventKey");
GlobalHost.DependencyResolver.UseRedis(redisConfig);

      

        
        
        
      

    

Everything worked fine, but I started getting the following exceptions.

Unhandled exception in Portal UI: System.InvalidOperationException: Queue full. at Microsoft.AspNet.SignalR.Messaging.ScaleoutStream.Send (Func2 send, Object state) at Microsoft.AspNet.SignalR.Infrastructure.Connection.Send(ConnectionMessage message) at Microsoft.AspNet.SignalR.Transports.TransportConnectionExtensions.SendCommand(ITransportConnection connection, String connectionId, CommandType commandType) at Microsoft.AspNet.SignalR.Transports.ForeverTransport.ProcessRequestCore(ITransportConnection connection) at Microsoft.AspNet.SignalR.PersistentConnection.ProcessRequestPostGroupRead(HostContext context, String groupsToken) at Microsoft.AspNet.SignalR.TaskAsyncHelper.FromMethod[T1,T2,T3,TResult](Func

4 func, T1 arg1, T2 arg2, T3 arg3) --- End of the stack trace from the previous place where the exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (task task) at System.Runtime.CompilerServices. TaskAwaiter.HandleNonSuccessAndDebuggerNotification (task task) at Microsoft.Owin.Mapping.MapMiddleware.d__0.MoveNext () --- end of the stack trace from the previous place where the exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThucrowForNonon tasks) in System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (task task) in Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContextStage.d__5.MoveNext () --- End of the trace where the stack was popped from the previous stack System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (Task Task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotificatio n (Task Task) at Microsoft.Owin.Security.Infrastructure.AuthenticationMiddleware1.<Invoke>d__0.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.Owin.Security.Infrastructure.AuthenticationMiddleware

1.d__0.MoveNext () --- End of the stack trace from the previous place where the exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessNotificationDebug (task task) at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContextStage.d__5.MoveNext () --- End of the stack trace from the previous place where the exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (task task ) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (task task) at Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.d__2.MoveNext () --- End of stack trace from the previous place where the exception was .Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End (IAsyncResult ar) in System.Web.HttpApplication.Asyn cEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute () in System.Web.HttpApplication.ExecuteStecution step

I looked at the redis cache. Everything seems to be in order. This is enough space.

What does "queue full" mean? What is this queue? How can I avoid such exceptions?