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 ('cc4903e0a3c625dcec130f5f78a73e57', -1, 1534470286, 1534470286, '36e137ae', 77, 0, 0)

Line : 187
File : sessions.php