Product details asks for authentication

-- url of the page with the problem -- : lojadocaopreto.com/index.php/verificacao...961-almeida-mario-de
-- HikaShop version -- : 2.6.4
-- Joomla version -- : 3.6.4
-- PHP version -- : 5.4.42
-- Browser(s) name and version -- : Chrome
-- Error-message(debug-mod must be tuned on) -- : Asks for authentication

I upgraded from Joomla 3.4.8 to 3.6.4 . No change in hikashop version, 2.6.4

After I upgraded I started to hava a problem with only one category,

When I try to access product details from that category, it appears a form asking for authentication.

I can't figure out what happened.

For instance, if I access to lojadocaopreto.com/index.php/novidades and choose any product, i'm forced to authenticate to see the details of the product

But if I access to lojadocaopreto.com/index.php/antiguidades2 and choose any product , I don't have to authenticate

Both menu are public

Thanks

Thanks

You were right.

I had "use canonical URL and generate it if missing" option activated.

I cleaned the field and everything stated working.