I work on Joomla 2.5 + with K2
I have more than one thousand contents (articles) written by one author (super-user), but I delete this author. Since that time, this message “JUser::_load : impossible de charger l'utilisateur ayant l'ID 909 » (unable to load user with ID 909) appears on the page.
So I change the author’s name in the content, and the message disappears.
How to change name of author in all items and in the same time ?
Thanks for your help.

Go in you database and then to this table "#_users" and search your Username and change the your ID to 909 and now is very important, that you remember your old ID. Because you need this again. So now you go to this table "#_user_usergroup_map" and now you looking for your old ID and change this with the new ID (909). But attention, thats is very dangerous. Please make first a backup from your website.

Hello,

Daniel has posted the correct solution. Furthermore you might find this post helpful www.joomlaworks.net/forum/k2-en/32083-how-to-change-author-id-in-database