Sometimes after importing orders via .csv and following the payment screen after applying postage it will come back with 'sorry there has been an error' .. please retry.

You cannot retry it does not work.
When looking at the orders they are all listed as FAILED however you can go into each order, one at a time and reprint label and it will oblige. You cannot reprint labels for more than one item at a time when they are in this state.

This has been bugging me for months as it takes plenty of unecessary time to manually select and reprint each shipping label.