Quote Originally Posted by Georgecy View Post
The link manager shows no links. And when trying to move the product in a new category it has no effect. It seems around 10 products which are related have no master category id
So, I created a product assigned to the test examples category. I then set the master_categories_id to '' for that product. I then went to Catalog->Categories/Products. Then I typed in the products_id that was associated with that product in the search field. The product appeared in the list. I then copied the product as a linked product to the category desired (at this point it was back to the Test Examples category). I then again went to "copy" the product but this time going to the link manager, I was presented with the product and the ability to change the master category through the dropdown selection.

So, then I followed the consideration previously described by lat9 about the products_to_categories table having bad information. In this case I removed all information from that table associated with my "problem" product. I again reset the master category to ''. So basically, the database would have data that there is a "product" but it isn't associated with anything.

This time, when I went through the copy as a linked product process, it appeared "successful" but the product did not appear anywhere other than by searching on its products_id. I then again attempted to access the link manager from the copy product action, and this time the series of checkboxes did not appear, but the product was shown at the top of the list and that there was an invalid master category assigned.

I admit that in a way I gave up trying to find a way to create a record in the products_to_categories table for this product at this point. But of course I thought, what about possibly moving the product? Nope, that wasn't a success either even though no message was provided on screen. A debug log was generated, but...

When I then added a record to the products_to_categories table for this one product even if it was to the main category I was then able to correct the issue as described above. So, yeah, first thing/important thing is to ensure that the products_id exists in the products_to_categories table in order to move forwards even if correcting this within the admin is otherwise not so easy, it still can be done until those options too are removed.