efcore.pg: NpgsqlOperationInProgressException with lazy loading after update to 3.0.1

Hello, i have a DBContext which uses LazyLoading. After update to PostgreSQL 3.0.1 i get an exception iterating linked entities. I could reproduce the problem with a simple console example.

working with: Microsoft.EntityFrameworkCore 2.2.6 Microsoft.EntityFrameworkCore.Proxies 2.2.6 Npgsql.EntityFrameworkCore.PostgreSQL 2.2.4

not working with: Microsoft.EntityFrameworkCore 3.0.0 Microsoft.EntityFrameworkCore.Proxies 3.0.0 Npgsql.EntityFrameworkCore.PostgreSQL 3.0.1

Code to reproduce:

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;

namespace postgresProblem
{
	public class DemoContext : DbContext
	{
		public static readonly ILoggerFactory MyLoggerFactory
			= LoggerFactory.Create(builder => { builder.AddConsole(); });

		public DemoContext()
		{
		}

		public DbSet<DemoEntity_1> DemoEntities { get; set; }
		public DbSet<DemoEntity_2> SubEntities { get; set; }
		protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
		{
			optionsBuilder.UseLoggerFactory(MyLoggerFactory).UseLazyLoadingProxies().UseNpgsql("Host=10.1.99.84;Port=30432;Username=postgres;Password=demo;Database=test");
		}
	}

	public class DemoEntity_1
	{
		public DemoEntity_1()
		{
			SubEntities = new List<DemoEntity_2>();
		}

		public int Id { get; set; }
		public virtual ICollection<DemoEntity_2> SubEntities { get; set; }
	}

	public class DemoEntity_2
	{
		public DemoEntity_2()
		{

		}

		public int Id { get; set; }
		public string Name { get; set; }
		public virtual DemoEntity_1 DemoEntity { get; set; }
	}

	class Program
	{
		static async Task Main(string[] args)
		{
			using (DemoContext context = new DemoContext())
			{
				if (await context.Database.CanConnectAsync() == true)
				{
					foreach (var demoEntity in context.DemoEntities)
					{
						foreach (var subEntity in demoEntity.SubEntities)	//here the OperationInProgress-Exception occurs
						{
							await Console.Out.WriteLineAsync(subEntity.Name);
						}
					}
				}
				else
				{
					await context.Database.EnsureCreatedAsync();
					//create some demo stuff
					DemoEntity_2 subEntity1 = new DemoEntity_2 { Name = "subEntity1" };
					context.SubEntities.Add(subEntity1);
					DemoEntity_2 subEntity2 = new DemoEntity_2 { Name = "subEntity2" };
					context.SubEntities.Add(subEntity2);

					DemoEntity_1 demoEntity_1 = new DemoEntity_1();
					demoEntity_1.SubEntities.Add(subEntity1);
					demoEntity_1.SubEntities.Add(subEntity2);
					context.DemoEntities.Add(demoEntity_1);

					await context.SaveChangesAsync();
					await Console.Out.WriteLineAsync("demo stuff created");
				}
			}
		}
	}
}

Exception thrown:

‘Npgsql.NpgsqlOperationInProgressException’ in Microsoft.EntityFrameworkCore.Relational.dll An exception of type ‘Npgsql.NpgsqlOperationInProgressException’ occurred in Microsoft.EntityFrameworkCore.Relational.dll but was not handled in user code A command is already in progress: SELECT d.“Id” FROM “DemoEntities” AS d

StackTrace:

   at Npgsql.NpgsqlConnector.<StartUserAction>g__DoStartUserAction|187_0(<>c__DisplayClass187_0& )
   at Npgsql.NpgsqlConnector.StartUserAction(ConnectorState newState, NpgsqlCommand command)
   at Npgsql.NpgsqlCommand.<ExecuteReaderAsync>d__102.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Threading.Tasks.ValueTask`1.get_Result()
   at System.Runtime.CompilerServices.ValueTaskAwaiter`1.GetResult()
   at Npgsql.NpgsqlCommand.ExecuteReader(CommandBehavior behavior)
   at Npgsql.NpgsqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
   at System.Data.Common.DbCommand.ExecuteReader()
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.QueryingEnumerable`1.Enumerator.MoveNext()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.Load[TSource](IQueryable`1 source)
   at Microsoft.EntityFrameworkCore.Internal.EntityFinder`1.Load(INavigation navigation, InternalEntityEntry entry)
   at Microsoft.EntityFrameworkCore.ChangeTracking.NavigationEntry.Load()
   at Microsoft.EntityFrameworkCore.ChangeTracking.CollectionEntry.Load()
   at Microsoft.EntityFrameworkCore.Internal.LazyLoader.Load(Object entity, String navigationName)
   at Microsoft.EntityFrameworkCore.Proxies.Internal.LazyLoadingInterceptor.Intercept(IInvocation invocation)
   at Castle.DynamicProxy.AbstractInvocation.Proceed()
   at Castle.Proxies.DemoEntity_1Proxy.get_SubEntities()
   at postgresProblem.Program.<Main>d__0.MoveNext() in C:\MyTemp\playground\postgresProblem\postgresProblem\Program.cs:line 60

Logger output

info: Microsoft.EntityFrameworkCore.Infrastructure[10403]
      Entity Framework Core 3.0.0 initialized 'DemoContext' using provider 'Npgsql.EntityFrameworkCore.PostgreSQL' with options: using lazy-loading proxies
info: Microsoft.EntityFrameworkCore.Database.Command[20100]
      Executing DbCommand [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT d."Id"
      FROM "DemoEntities" AS d
info: Microsoft.EntityFrameworkCore.Database.Command[20100]
      Executing DbCommand [Parameters=[@__p_0='?' (DbType = Int32)], CommandType='Text', CommandTimeout='30']
      SELECT s."Id", s."DemoEntityId", s."Name"
      FROM "SubEntities" AS s
      WHERE ((s."DemoEntityId" = @__p_0) AND ((s."DemoEntityId" IS NOT NULL) AND (@__p_0 IS NOT NULL))) OR ((s."DemoEntityId" IS NULL) AND (@__p_0 IS NULL))
fail: Microsoft.EntityFrameworkCore.Database.Command[20102]
      Failed executing DbCommand (5ms) [Parameters=[@__p_0='?' (DbType = Int32)], CommandType='Text', CommandTimeout='30']
      SELECT s."Id", s."DemoEntityId", s."Name"
      FROM "SubEntities" AS s
      WHERE ((s."DemoEntityId" = @__p_0) AND ((s."DemoEntityId" IS NOT NULL) AND (@__p_0 IS NOT NULL))) OR ((s."DemoEntityId" IS NULL) AND (@__p_0 IS NULL))
fail: Microsoft.EntityFrameworkCore.Query[10100]
      An exception occurred while iterating over the results of a query for context type 'postgresProblem.DemoContext'.
      Npgsql.NpgsqlOperationInProgressException: A command is already in progress: SELECT d."Id"
      FROM "DemoEntities" AS d
         at Npgsql.NpgsqlConnector.<StartUserAction>g__DoStartUserAction|187_0(<>c__DisplayClass187_0& )
         at Npgsql.NpgsqlConnector.StartUserAction(ConnectorState newState, NpgsqlCommand command)
         at Npgsql.NpgsqlCommand.ExecuteReaderAsync(CommandBehavior behavior, Boolean async, CancellationToken cancellationToken)
         at Npgsql.NpgsqlCommand.ExecuteReader(CommandBehavior behavior)
         at Npgsql.NpgsqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
         at System.Data.Common.DbCommand.ExecuteReader()
         at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
         at Microsoft.EntityFrameworkCore.Que
C:\MyTemp\playground\postgresProblem\postgresProblem\bin\Debug\netcoreapp3.0\postgresProblem.exe (process 22484) exited with code -1.

Is this a problem with the PostgreSQL package or with the EntityFrameworkCore package?