These errors are primarily caused by incorrect or missing data in NetSuite.
This error occurs if item
X is inaccessible to the subsidiary associated with the customer of the invoice or order. NetSuite considers an item "inaccessible" if the item is not associated with the subsidiary directly, or if the customer subsidiary is not a child of a parent subsidiary which the item is associated with.
This could also occur if there is not an income account set on the item record.
Solution: change the subsidiary associated with the item. The easiest solution is to pick the parent subsidiary and ensure "Include Children" is checked.
This indicates that the income account for the item is not set in NetSuite.