Problem
You want to cancel a purchase order, but the option is missing, or you get an error message when you try.
Why this happens
You can only cancel purchase orders where the lot or lots created on the order are not allocated to (i.e. selected on) subsequent orders, for example a production order, a sales order, or a warehouse order.
If part of a lot is allocated to another order, you will instead get the error message "Quantity available on the lot cannot be negative", along with an indication of which lot the error concerns. The error message only shows one lot-number at a time, so you may see the error repeatedly until you have removed all allocations of the order's lots.
How to fix it
Cancel the order
Go to the purchase order you want to cancel.
Click the purple action button in the top right corner.
Select Cancel Order from the dropdown menu:
NB: If the option to cancel the order is missing, it has been hidden in the base settings for purchase orders in Company settings. You can read more about company settings for purchase orders.
Remove allocations if you get an error message
Click the blue button on the right side of the lot line on the purchase order, and select Go to lot:
View all movements for the lot at the bottom of the page:
Go to each of the orders and remove the lot.
NB: If the lot has been used on a sales order that has already been invoiced, you must credit the invoice before you can remove the lot from the sales order. Then complete the sales order by selecting the correct lot, and create a new invoice.
Once all allocations have been removed, only the incoming purchase order should remain in the movements for the lot. You can then cancel the purchase order.