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 ('e3818ea21ab2c869fb754988f6c8ee84', -1, 1397890301, 1397890301, '36c41867', 25, 0)

Line : 170
File : sessions.php