Problem for new users in RT 3.8.2 " RT could not load a valid user"

RT Users
1

Hello,

Since my migration from 3.6.6 to 3.8.2, I get this message for
requests from new users :

RT could not load a valid user, and RT’s configuration does not allow
for the creation of a new user for this email (xxxx.xxxx@xxx.com).

You might need to grant ‘Everyone’ the right ‘CreateTicket’ for the
queue incoming.

And of course, I have this right on the “incoming” queue. How can I fix this ?

Thanks!
L.B.