Incorrect item category for revenue or expenditure item

What causes this issue?

You have entered <DS:GLOS.item_category>item category</> 1 (cash
balance item). Cash balance items must have
<DS:GLOS.financial_transaction>financial transaction</> 90 (Post
payment).

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Check your input or change the financial transaction to 90 if you want
to enter a cash balance item.
If you want to enter a revenue or expenditure item, change the item
category to 2 (revenues) or 3 (expenditures).

Error message extract from SAP system. Copyright SAP SE.