Well is solved now, here the details might be useful for someone else.
The problem starts after move/copy the site to other hosting, everything works well but the children pages and new pages refer to a 500 error inside the manager.
After several hours and many attempts I found the problem in one of the templates
for any weird reason (don't understand why) the default template ID-1 was corrupt on the transfer, even when it was working right on the main site.
Anyway, the reason that only the children has the problem was because all the children has the template ID-1 as selected template and the new pages didn't work because the default template was the ID-1 too.
So, change the template on the DB solved the problem.
stupid but true and very annoying problem.
hope save time to someone else.
Cheers.
[ed. note: Ysanmiguel last edited this post 10 years, 7 months ago.]
