I am trying to build a Http API By C#. After returning the HTTP Response, I need to do some works and then update the database in the background.

However, I guess the DBContext instance is disposed automatically after the returning the API response, therefore, this error shows up:

“System.ObjectDisposedException: ‘Cannot access a disposed context instance. A common cause of this error is disposing a context instance that was resolved from dependency injection and then later trying to use the same context instance elsewhere in your application”

Here is my Code:

public async Task<DBmodel> GetAttachmentsListById(Guid Id, bool RequestSync)
{
    var target = await Repository.GetDBmodelById(Id);
    if (target != null)
    {
        if (RequestSync)
        {
            SyncAttachment(target);
        }
        if (target != null)
        {
            
            return DBmodel
        }
    }
    
    return null!;
}

public void SyncAttachment(DBmodel target)
{
    _serviceProvider = serviceProvider;
    var executeScope = _serviceProvider.CreateScope();
    var ServiceProvider = executeScope.ServiceProvider;
    var repository = ServiceProvider.GetRequiredService<Repository>();
    Action a = async () =>
    {
        ExternalClient Client = new ExternalClient();
        var ExternalResult = await //Get External Information
        if (//NeedUpdate)
        {
            foreach (var x in ExternalResult )
            {
                    var model = new DBmodel;
                    model = ExternalResult;
                    await repository.UpDateDBmodel(att);//Exception Occurs Here
            }
        }
    };
    Task task1 = Task.Factory.StartNew(a);
    task1.ContinueWith( c =>
    {
        executeScope.Dispose();
    });
}