Error: "The invoice number has already been used..."

Error: "The invoice number has already been used for another client. Do you want to continue?" when posting an invoice or payment in Sage 50 Accounting.

Manually adjust the invoice number to the next valid number

1. In the Sales invoice window, click Sales, Adjust Invoice.
2. Search then open the invoice you want to adjust.
3. Change Invoice No. to the desired number.
4. Click Post (or Process).

The system will create a reversal of the original invoice and an invoice with correct numbers with a new journal entry number.

To prevent duplicate invoice numbers in the future

1. Go to File, Switch to Single-user Mode.
2. Go to Setup, Settings, Company, Forms.
3. Select the Check for Duplicates box for the applicable form.
4. Click OK.