I can not access the administration website, the error is "internal server error".
In the log I get this:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/web/application.py", line 237, in process
    return p (lambda: process (processors))
  File "/usr/lib/python2.7/dist-packages/web/session.py", line 84, in _processor
    self._cleanup ()
  File "/usr/lib/python2.7/dist-packages/web/session.py", line 172, in _cleanup
    self.store.cleanup (timeout)
  File "/usr/lib/python2.7/dist-packages/web/session.py", line 319, in cleanup
    self.db.delete (self.table, where = "$ last_allowed_time> atime", vars = locals ())
  File "/usr/lib/python2.7/dist-packages/web/db.py", line 907, in delete
    self._db_execute (db_cursor, q)
  File "/usr/lib/python2.7/dist-packages/web/db.py", line 587, in _db_execute
    out = cur.execute (query, params)
ProgrammingError: the "sessions" relationship does not exist
LINE 1: DELETE FROM sessions WHERE '2018-11-24T10: 13: 17.721133' :: tim ...
                    ^

172.18.32.67 [pid: 1431 | app: 0 | req: 5/5] 10.50.252.52 () {52 vars in 917 bytes} [Sat Nov 24 10:43:17 2018] GET / iredadmin => generated 21 bytes in 4 msecs (HTTP / 1.1 500) 1 headers in 63 bytes (2 switches on core 0)

It's a new installation, the version is 0.9.8 and I'm using nignx.

Thanks and regards