In my case, the error was when generating the payment, I was missing the writeoff_account_id field, just send the id you need from the account.account model and there should be no problem

payment = Payment.create({
'writeoff_account_id': self.env['account.account'].browse("you id").id,
})

1. You have to make sure there are only positive numbers in your import sheet; so -123 credit should be converted into 123 debet
2. You have to make sure that you add a 'suspense' line as the latest line to balane your import; i.e. add the absolute value of the sum of all your credits - sum of all debets, and put that in the credit column if the sum of debet > sum of credit; else put it in the debet column

Hope this helps.

Hello Haffis, 

I got the same error and fixed it like this: should be no lines where both "CREDIT" and "DEBIT" are not empty.

P.S. I also checked: if you set, for example, "0" into column "credit" where "debit" is not 0  - it doesn't affect the error.