"Cannot access a disposed object. Object name: 'MySqlConnection'." when trying to persist 35 MB to MariaDb.

Steps to reproduce

Please take a look at https://github.com/jp7677/hellocoreclr/tree/mariadb. When running the app I can reproduce the error by enter some text and press the “Say Hello” button. Entity and dataservice are pretty straight forward (relevant parts):

 public class Greeting
 {
   public int GreetingId { get; set; }
   public byte[] SomeHugeFile { get; set; }
}

var somehugeFile = new byte[35* 1000 * 1000];
using(var db = dbContextFactory.CreateHelloWorldDbContext())
{
  db.Greetings.Add(new Greeting
  {
    Name = greeting,
    TimestampUtc = DateTime.Now.ToUniversalTime(),
    SomeHugeFile = somehugeFile
   });
  await db.SaveChangesAsync();
}

The issue

I’m trying to save 35MB to the database in an ASP.Net Core request, unfortunately it ends with a ObjectDisposedException.

An unhandled exception was thrown by the application.
System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'MySqlConnection'.
   at MySql.Data.MySqlClient.MySqlConnection.VerifyNotDisposed()
   at MySql.Data.MySqlClient.CommandExecutors.TextCommandExecutor.<ExecuteReaderAsync>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySql.Data.MySqlClient.CommandExecutors.TextCommandExecutor.<ExecuteNonQueryAsync>d__1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySql.Data.MySqlClient.MySqlCommand.<ExecuteNonQueryAsync>d__46.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()
   at MySql.Data.MySqlClient.MySqlTransaction.Dispose(Boolean disposing)
   at MySql.Data.MySqlClient.MySqlConnection.CloseDatabase()
   at MySql.Data.MySqlClient.MySqlConnection.DoClose()
   at MySql.Data.MySqlClient.MySqlConnection.Dispose(Boolean disposing)
   at Microsoft.EntityFrameworkCore.Storage.Internal.MySqlRelationalConnection.Dispose()
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.Dispose()
   at Microsoft.EntityFrameworkCore.DbContext.Dispose()
   at HelloCoreClrApp.Data.DataService.<SaveGreetingAsync>d__5.MoveNext() in /home/jpeters/Develop/hellocoreclr/src/HelloCoreClrApp/Data/DataService.cs:line 61
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at HelloCoreClrApp.WebApi.Actions.SayHelloWorldAction.<SaveGreetingAsync>d__4.MoveNext() in /home/jpeters/Develop/hellocoreclr/src/HelloCoreClrApp/WebApi/Actions/SayHelloWorldAction.cs:line 34
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at HelloCoreClrApp.WebApi.Actions.SayHelloWorldAction.<ExecuteAsync>d__3.MoveNext() in /home/jpeters/Develop/hellocoreclr/src/HelloCoreClrApp/WebApi/Actions/SayHelloWorldAction.cs:line 26
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at HelloCoreClrApp.WebApi.HelloWorldController.<SayHelloWorldAsync>d__3.MoveNext() in /home/jpeters/Develop/hellocoreclr/src/HelloCoreClrApp/WebApi/HelloWorldController.cs:line 26
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionMethodAsync>d__27.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextActionFilterAsync>d__25.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ActionExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeNextResourceFilter>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeAsync>d__20.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Hosting.Internal.RequestServicesContainerMiddleware.<Invoke>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Server.Kestrel.Internal.Http.Frame`1.<RequestProcessingAsync>d__2.MoveNext()
2017-03-31 11:17:22 +02:00|Debug|10|0HL3O2QSK80BB|Microsoft.AspNetCore.Server.Kestrel

Further technical details

MySQL version: MariaDb 10.1.22-MariaDB-1~jessie - mariadb.org binary distribution Operating system: Fedora 25/Docker Pomelo.EntityFrameworkCore.MySql version: PackageReference Include=“MySqlConnector” Version=“0.15.1” PackageReference Include=“Pomelo.EntityFrameworkCore.MySql” Version=“1.1.1-prerelease-10026”

[jp7677]

Yeah, cool! Thanks a lot. Its a pleasure to use this project (and the underlying MySqlConnector of course ) and to work with you!

[caleblloyd]

I’ve opened #247, my local copy of your test with that commit now produces:

Failed   Pomelo.EntityFrameworkCore.MySql.PerfTests.Tests.Models.ExpressionTest.LargeObject
Error Message:
 System.AggregateException : One or more errors occurred. (An error occurred while updating the entries. See the inner exception for details.) (MySqlSession is not connected.)
---- Microsoft.EntityFrameworkCore.DbUpdateException : An error occurred while updating the entries. See the inner exception for details.
-------- MySql.Data.MySqlClient.MySqlException : Error submitting 14MB packet; ensure 'max_allowed_packet' is greater than 14MB.
------------ System.Net.Sockets.SocketException : Broken pipe
---- System.InvalidOperationException : MySqlSession is not connected.