This one is the mistake that gives....

Can not proceed: possible CSRF/XSRF attack!

Since I avoid it?

It, again, may come from the upgrading process.

If you have had an older version of the board, try to install a default version first, upgrading your database. That all should work in the default version. You will find such instructions under Upgrading / Migrating FAQ.

The databases are updated, the only thing that I have supported they are the files of the folder templates.

Thank you for your response.
Juan Carlos

The files are very important in that aspect, specially template forms, variables and PHP scripts. Take your upgrade carefully.

It is difficult for the great quantity of changes realized for my in the original code, but I will try it.

Thank you for your response .

Juan Carlos

Sometimes it's better to improve the code starting it from the scratch, but I'm sure any kind of custom modifications could be upgraded following our instructions. Have a try :-)

Resolved problem:

Only it was necessary to introduce in the page "main_posts.html" the corresponding code with to the javascript of control of the cookie "getCSRFCookie".

Thank you very much
Juan Carlos

PD.: might you change the image that you have in the gallery of Webs of udias.com? We have changed very much...

I think that I have this same problem. Just wanna know how fix that cookie?

You don't have to fix the cookie or modify the code some other way.
First better know out why it's happening. Better configure your board to run without this error. In most cases, it's a question to improper configuration and settings.

If you will fix that manually and without knowing what you do, you can get in serious troubles sooner or later, because it's a security question.