Entity framework core The instance of entity type cannot be tracked because another instance with the same key value

Question

I have a method to update a Factor, but when I execute method it not work.

this is error:

exception {"The instance of entity type 'BorrowToolFactor' cannot be tracked because another instance with the same key value for {'BorrowToolFactorId'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values."} System.Exception {System.InvalidOperationException}

public static long Save(BorrowToolFactor borrowToolFactor, List<BorrowTool> borrowTools)
    {
        CheckQueryResult.ResultError = string.Empty;

        long _result = 0;

        using (var context = new StoreManagerContext())
        {
            try
            {
                    _result = orginalBorrowToolFactor.BorrowToolFactorId;
                 
                    context.Entry(orginalBorrowToolFactor).CurrentValues.SetValues(borrowToolFactor);

                    #region DeleteOriginalBorrowTool

                    var originalBorrowTool = context.BorrowTools.Where(_borrow => _borrow.BorrowToolFactorId == _result).ToList();

                    context.BorrowTools.RemoveRange(originalBorrowTool);

                    #endregion DeleteOriginalBorrowTool

                    #region AddNewBorrowTools

                    borrowTools.ForEach(_borrow => _borrow.BorrowToolFactorId = _result);

                    context.BorrowTools.AddRange(borrowTools);

                    #endregion AddNewBorrowTools

                }
                context.SaveChanges();
            }
            catch (Exception exception)
            {
                _result = 0;
                CheckQueryResult.ResultError = "Error: " + exception.Message;
            }
            return _result;
        }
    }

error happen on this line: context.BorrowTools.AddRange(borrowTools);

I use same method for another table worked correctly but this method not working.

Answer 1

I use this code instead of context.BorrowTools.AddRange(borrowTools); and it worked. I don't know why context.BorrowTools.AddRange(borrowTools); not worked.

borrowTools.ForEach(_borrow => {
                        context.Entry(_borrow).State = Microsoft.EntityFrameworkCore.EntityState.Added;
                    });