ERR_EXPENSE_CATEGORY on QuickBooks: Expense category missing. Root cause: The expense account or category referenced in the transaction has not been set up in the chart of accounts, has been deactivated, or is not configured for the type of expense being recorded. Each expense must be assigned to a valid, active account code that is appropriate for the transaction type and entity. Step 1: Check category. Verify category exists Step 2: Create category. Add missing category Step 3: Assign category. Link to expense Step 4: Retry entry. Attempt entry again