School principals say errors in Wednesday's school pay round have left them chasing staff for thousands of dollars of holiday pay.
The Novopay system delivered a payday overnight in which some staff were paid too much holiday pay, others were paid too little and 5000 were not paid at all.
Principals say the errors involve staff who are paid directly from school accounts and that could cause financial problems for schools.
They say it might be difficult to get money back from overpaid staff because many no longer work for them and some have gone overseas.
Novopay told schools it balanced the error by including deductions in Wednesday's pay, but principals say that is not how it looks to them.
Novopay says the unpaid staff will be paid on Thursday and another of the errors will be fixed in next week's pay.
Principals are unhappy that new problems are emerging in the Novopay system even though the Ministry of Education and the company behind the system, Talent2, have been working to fix it.
Secondary Principals Association president Patrick Walsh says the latest problems are evidence of bungling and incompetence.
He says it does not look like the problems with Novopay are being fixed and they are causing unnecessary stress.