You are seeing the below error message after trying to publish an invoice.

Input string was not in a correct format.

This error can occur if an unknown character or symbol is included in an Invoice number, line item, reference, or description.

Some accounts packages do not allow some characters. e.g: { } [ ] ' ~, among others, to be exported.

To clear this error, simply open the invoice and delete any special characters from the extracted fields and the invoice will publish.

This error can also indicate that a VAT code needs to be selected on the company's Integrate page. Once that is done, the invoice just needs to be republished!