I have the following code:

List<MyEntity> lstAllMyRecords = miDbContext.MyEntity.ToList<MyEntity>();

foreach MyEntity iterator in lstMainRecord)
{
    tasks.Add(
        TaskEx.Run(() =>
            {
                try
                {
                    checkData(lstAllMyRecords.Where(n => n.IDReference == iterator.IDReference).ToList<MyEntity>());
                }
                catch CustomRepository ex)
                {
                    //handle my custom repository
                }
                catch (Exception)
                {
                    throw;
                }
            })
        );
}//foreach

Task.WaitAll(tasks.ToArray());

I get all the records from my data base and in the foreach loop, I group all the records that have the same IDReference. Thenk I check if the data is correct with the method chekData.

The checkData method throw a custom exception if something is wrong. I would like to catch this exception to handle it.

But the problem is that with this code the exceptions are not caught and all seem to work without errors, but I know that this is not true.

I try to check only one group of records that I know that has problems. If I check only one group of registrers, the loop is execute once and then only task is created. In this case the exception is caught, but if I have many groups, then any exception s thrwon.

Why when I only have one task the exception is caught and with many groups are not?

Thanks.