phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO mex2mex_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('5a99c2b1c10edbff66628cf4c10f8871', -1, 1406689050, 1406689050, '17142c88', 5, 0)

Line : 170
File : sessions.php