Re: Hosting change: impossible to login or register.
Listening to _ck_, I’ve worked a little around the settings in the database. I found that some settings are stored in the bb_topicmeta table. There are some records with topic_id “0”. Obviously there are no topics with id 0 – so I deduced that are general settings.
I’ve just took the values generated by the fresh installation and put them in the old database. Now everything works fine.
Thank you all for help; particularly to _ck_ that sent me to the right way.