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, session_admin) VALUES ('5253ec571b103dc370b9b14f464b6791', -1, 1280531859, 1280531859, '266bbf77', 12, 0, 0)

Line : 187
File : sessions.php