phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('a8a091907afe4371f99ca4e240bfdfa3', -1, 1406229698, 1406229698, '3651b18c', 11, 0)

Line : 315
File : sessions.php