Here is a copy of the message I receive, I have no idea what went wrong
Internal Server Error
Oops, something went wrong!

Error:

Caught exception in MusicBrainz::Server::Controller::ReleaseEditor::Add->add "No artist was created for Serge Reggiani at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Wizard/ReleaseEditor.pm line 832."
Stack trace:
line 832 MusicBrainz::Server::Wizard::ReleaseEditor
line 777 MusicBrainz::Server::Wizard::ReleaseEditor
line 93 MusicBrainz::Server::Wizard::ReleaseEditor
line 23 MusicBrainz::Server::Controller::ReleaseEditor::Add
line 270 MusicBrainz::Server
Request data:

$VAR1 = {
'query_parameters' => {},
'body_parameters' =>

{ 'save' => 'Enter edit', 'edit_note' => 'I currently have the cd', 'wizard_session_id' => '0.148460367481022' }

};

URL: http://musicbrainz.org/release/add

I was creating a cd "Boris Vian chanté par ..." as a compilation, and Serge Reggiani is the first artist of the compilation