phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 144 Table './phpbb/phpbb_sessions' is marked as crashed and last (automatic?) repair failed

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('251825d5c96236c989382c9a4fc0c73b', -1, 1455093380, 1455093380, 'b848b1b6', -1, 0, 0)

Line : 189
File : sessions.php