401K loan deduction stopped by payroll error must default.

After a few years of corporate schuffling and outsourcing of payroll, I recently found out after a second 401K fund management transfer by the employer that I have 24 hours to settle a 401K loan or defualt since the payroll firm suddenly stopped my payroll deduction for the loan payments over 6 quarters ago. The reason I did not catch it is I recieved a pay raise and also increase my pre-tax 401K deduction so my net pay was lower than the previous year (thus not see a jump in my dorect deposits).

My employer states it is my fault but I never initiated the stoppage of the deductions as it was an error in the payroll outsourcing transition. Is the employer, payroll firm, or the 401K fund manger liable?

I must default as I do not have they money to pay off the loan.