AccountHeaderNotAllowed

When POSTing to the Sales or Purchases endpoints you may encounter the error AccountHeaderNotAllowed.

    {
            "Name": "ValidationError",
            "Message": "BusinessLine_AccountHeaderNotAllowed",
            "AdditionalDetails": "AccountId:(SaleEventItemLine)",
            "ErrorCode": 4244,
            "Severity": "Error",
            "LearnMore": null
        },

The error is being returned because the account that has been used is a Header Account. You are unable to POST using a Header Account. The account that is used on the Sale/Purchase will need to be a Detail Account. We recommend checking if an account is a Detail or Header Account, you can complete a GET request using the endpoint /GeneralLedger/Account

 "IsHeader": true, 

or 

"IsHeader": false,

Detail accounts—sometimes called sub-accounts, these are the accounts to which you allocate transactions.

Header accounts—these accounts group related detail accounts to help you organise your accounts list.

Please note:

You cannot allocate transactions to a header account.
The balance of a header account is the sum of the detail accounts indented directly below it.
You can have up to three header account levels.
How you group your accounts can affect how totals and subtotals are calculated on reports.
Top-level header accounts, such as 2-0000, cannot be edited.

From the UI: The header and detailed account are displayed as below:

Create a Header and Detailed Account

Header Account