CorruptError: CorruptError: database disk image is malformed

As of this afternoon i have this problem. It has worked fine even this morning.

Traceback (most recent call last):
File "site-packages/calibre/gui2/device.py", line 88, in run
File "site-packages/calibre/gui2/device.py", line 506, in _books
File "site-packages/calibre/devices/kobo/driver.py", line 1810, in books
File "site-packages/calibre/devices/kobo/driver.py", line 1685, in get_bookshelvesforbook
File "src/cursor.c", line 231, in resetcursor
CorruptError: CorruptError: database disk image is malformed

i have logged out of kobo. restarted calibre.
but keep getting this message.
is there anyone who can help me out here.

thanks.