SEO friendly URLs do not accept "{rewrite}_{id}.html" for categories

[serpeal79]

Hi, people.

 

I'm trying to move from my OSCommerce to Prestashop, but I do not want to loose the SEO work in my old site, so I'm trying to force Prestashop categories and products to have the same url than my OSCommerce categories and products.

 

Now I'm working with categories, and I've activated SEO + URLs in preferences.

 

This is a category URL in OSCommerce:

 

altavoces-autoamplificados-gama-amplia-full-range-altavoces-autoamplificados-c-38_205_400_78_742.html

 

The last number before .html is the category id (742), and the rest numbers before are the parent ids until category 0.

 

So I thought I could force (in Prestashop)

 

altavoces-autoamplificados-gama-amplia-full-range-altavoces-autoamplificados-c-38_205_400_78

 

as the category friendly url and then put the rule

 

{rewrite}_{id}.html

 

in SEO + URLs, but this doesn't work. The links in the front end show properly, but when clicked they show a blank page.

 

If I can't do it I'll have to build redirections for all my old categories urls to the new ones to keep my SEO work, but that

 stinks.

 

Any suggestion to achieve this?

 

Thanks in advance.