phpBB : Critical Error

Error creating new sessions

DEBUG MODE

SQL Error : 1062 Duplicate entry 'acc39fddd8aff0f2b6478688a42a6cc8' 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 ('acc39fddd8aff0f2b6478688a42a6cc8', -1, 1505821999, 1505821999, '365c9e41', 4, 0, 0)

Line : 187
File : sessions.php