in case someone else happens...
There are two possible solutions and it usually occurs at two specific points.
First point: when you open a paid order to add some other product because the customer has requested it... If you try to search for the product, no results appear (the internal search does not work) --> then it must go to your database in the ps_products_attribute table, edit the "REFERENCE" section of one of the products and then edit the line inline so that it reads this command: UPDATE `ps_product_attribute` SET `reference` = ''" all references must be empty or full, not you can mark NULL.
The second point where it happens is when you try to create an order from a customer abandoned order, you try to "USE" the abandoned order to load the product(s)... but it doesn't work... it also doesn't let you add it manually... at this point you go to the product and modify one letter of the name by adding a space to fix it and it will work again.
