You are seeing the below error after trying to publish an invoice.
Unsupported Feature: DueDateForSalesInvoice
Sage 50 UK&I integrated companies.
This error can occur as we unfortunately do not support default due dates for Sales invoices on companies integrated with Sage 50UK&I.
If you notice this error after trying to publish an invoice you will need to check your Company Settings to make sure you do not have a default due date selected:
You will find your Company Settings on the left hand side of your company homepage.
Scroll down to the Sales section of Accounting Settings. If you have a Default Due Date set, you just need to change it to Not Required and make sure you save the changes!
Re-publish the affected sales invoice(s).