Quote error - The item category ‘ZAGZ’ is not permitted for product xxxxxx-xxxx-xxx.

In the Sales Quotation, click on edit, go to column Item Category, go to the item number and change the drop-down in Item Category.  If it is Item (LEIS), change to Item (NORM) or Item (DIEN).  Whatever the Item Category may be, change it to something different, Item (LEIS), Item (NORM), or Item (DIEN).

If the column Item Category is not visible, go to the pencil in the Item assignment block and add Item Category.

I don't what this all means, or where it comes from, but I know that changing the drop-down in the Item Category will make the error disappear.