phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 'session_user_id'

INSERT INTO forum_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('7e82e0c2b6b8289ad68f18dec9794961', -1, 1540318083, 1540318083, '36c6d41e', 4, 0, 0)

Line : 187
File : sessions.php