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 ('602035da33eca9125320d7ca3836c828', -1, 1414829041, 1414829041, '36a78a35', 20, 0, 0)

Line : 187
File : sessions.php