Question J! 2.5.7 + sh404SEF 3.6.4.1481: Can't create account (invalid token) if SEF and URL rewriting set on

No,
I just publish the Joomla Login module and get same error when register. The problem is not the login but register.
I change language to english and again same error.

during develop mode it was working I'm quite sure. Then I make an update in BT Content Slider and jw_sigpro. A few weeks later the problem starts

nuno wrote: No,
I just publish the Joomla Login module and get same error when register. The problem is not the login but register.
I change language to english and again same error.

As I thought, this proves that the problem has nothing to do with Kunena. See msg #2 of How do I register new users to my website and where should they login to use my website? where you will see, in large letters:

Kunena is not responsible for user registration or login to your website

You have a user registration problem but it has nothing to do with Kunena. I suggest you try When all else fails, try this

As far as the other extensions are concerned, (BT Content Slider and jw_sigpro), we know nothing about these things or whether they are affecting your site. At this point I am just guessing. Perhaps the problem is caused by some setting change you have made in Joomla Global Configuration. Put the values back to their original settings and see if this fixes the problem and then change, one by one, the settings until the problem occurs again.