Update:

after making the suggested change, I now have two problems...

before, by clicking on a sold out product, you could still see the technical sheet.
Now, the page refreshes and takes you to the home page.

Second problem...

before editing, by clicking on the main category, compare all the products I had selected...
Now,if I select the main category...i just get a refresh 

Goodmorning everyone,I would need your help.

For the first time I used AbanteCart for an e-commerce and how user friendly it seems,I have two problems that I cannot solve.

I have create a Categories with related sub-categories.

if I select the category,i receive a 404 Error (The requested URL was not found on this server.)
yet the products are listed both in the main category and in the sub-category.

Thanks a lot in advance.

(can I post my e-commerce link to show the error?)