I got this error few days back. U might have changed product categories for some products. In that case go to Inventory--> Configuration --> Product categories --> Check --> Income and Expense accounts are same for all product categories.

Hi,

I have faced a similar issue and in my case, I figured it like this,

*please check inside your journal if the outstanding receipts account is set for both incoming and outgoing payments?

*Also, inside the customer, make sure you have set the account payable and receivable.

Thanks