RadzenDataGrid problem in all components

Hi! Everything worked fine till today. In every component where I've used RadzenDataGrid throws me this Exception

 Microsoft.AspNetCore.Components.Server.Circuits.CircuitHost[111]
      Unhandled exception in circuit 'zRdFFGlFSUQS6fQdcOh7LZ4N6Gg5zAHnJKnAP6YvVIQ'.
      System.ArgumentNullException: Value cannot be null. (Parameter 'source')
         at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
         at System.Linq.Enumerable.Count[TSource](IEnumerable`1 source)
         at NetWebClient.Components.Devices.IndexComputers.<BuildRenderTree>b__0_9(RenderTreeBuilder __builder2)
         at Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.AddContent(Int32 sequence, RenderFragment fragment)
         at Radzen.Blazor.RadzenStack.BuildRenderTree(RenderTreeBuilder __builder)
         at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment, Exception& renderFragmentException)
 System.InvalidOperationException: BeginExecuteReader requires an open and available Connection. The connection's current state is closed.

Here is a sample from datagrid:


On page loading "OnInitializedAsync" calls two services for initial data:

 SELECT TOP(1) [d].[Id], [d].[CreatedAt], [d].[DeletedAt], [d].[LastModifiedBy], [d].[ModifiedAt], [d].[TypeName]
      FROM [DeviceTypes] AS [d]
      WHERE [d].[TypeName] = @__name_0
fail: Microsoft.EntityFrameworkCore.Query[10100]
      An exception occurred while iterating over the results of a query for context type 'NetWeb.Infrastructure.NetDbContext'.
      System.InvalidOperationException: BeginExecuteReader requires an open and available Connection. The connection's current state is closed.
         at Microsoft.Data.SqlClient.SqlCommand.<>c.<ExecuteDbDataReaderAsync>b__211_0(Task`1 result)
         at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
         at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
      --- End of stack trace from previous location ---
         at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
         at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
      --- End of stack trace from previous location ---
         at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()

After trying to load some page component it throws me next error:


According to this error I suggest that db connection is disposed, but it worked perfectly before. When I remove RadzenDataGrid content there is no problem with connection and services works fine.

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