You will receive this error message when the value you are entering into the Cost Account field isn't valid. It could be that the Cost Account has been mistyped or that you've accidentally entered a Ledger Account in the Cost Account Field.
To fix the error, review the line with the mentioned Cost Account and select a valid option. The Cost Account field has a drop-down list, so you can choose from the list instead of typing. You can also use wildcards where appropriate for Cost Accounts. The wildcards are % for multiple characters or _ for single characters.