phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'a23acbc2e2dc506331d82319b3452ddb' for key 1

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('a23acbc2e2dc506331d82319b3452ddb', -1, 1462152123, 1462152123, '36f2fdcf', 19, 0, 0)

Line : 187
File : sessions.php