phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' 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 ('affe36b4c40fa0f98ee2ec4a5e488516', -1, 1544410531, 1544410531, '36520adb', 4, 0, 0)

Line : 187
File : sessions.php