@karmakoma
I have but not used ...as far as I have understood I need it to make these "forms" working, which they don´t...
Right, but do you have it installed? Try removing the LDAP plugin and see if that makes it work.
You need to see the response data in the network tab, not the 500 error.
Can you explain better the passages?? It would be very usefull!
I'm not sure what you mean by this, can you further explain?
Cheers.