While you are trying to cancel a document, you may receive the following message:"You cannot issue this Document as there is not enough availability in the inventory location selected for product: [NameOfYourProduct]. Negative stock is not supported. Availability is not updated."
The reason is, you are canceling a document (Goods In) that brought in stock which was then sold. If you were allowed to cancel this, you would end up with negative stock at some point in history for the items listed in the warning message.
To be able to cancel this document you should cancel the Goods Out document(s) that shipped those items after the Goods In was issued. After that, you will be able to cancel the Goods In.
Finally, after these two cancellations, you need to re-issue both documents.
Or login to your account.