Why is this happening?
This error can occur when printing an invoice if there have been certain changes made to the invoice template.
How to fix this error?
The first step is to go to Setup>Firm Settings>Invoice Templates
Find your usual template and click edit.
If you’ve only made minor changes and for a fast fix, we encourage you to close the template and click “Restore” to the right. This will remove any changes are restore to your template to its original. You can now try to print your invoice again.
If you’ve made many changes to your invoice, we encourage you to contact our support team, and we can try to work with you to discover the issue.