phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '0' for key 'session_user_id'

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('ade9f1f031091f56c0fc84d8847c37c6', -1, 1540307359, 1540307359, '365ca369', 77, 0, 0)

Line : 187
File : sessions.php