phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('c04eef2ec1fe4655a102302a69a48d95', -1, 1414248110, 1414248110, '36a354c7', -1, 0)

Line : 152
File : /var/www/vhosts/fuenlabrada.com/httpdocs/phpbb/includes/sessions.php