phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry 'b15e2bcb5cc7b5f6d1dbdf0628021504' for key 1

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('b15e2bcb5cc7b5f6d1dbdf0628021504', -1, 1216927857, 1216927857, '26673f11', 176, 0, 0)

Line : 187
File : sessions.php