Fujitsu ScanSnap N1800 Operator's Manual page 291

Code
7A040018 Restore failed.
7A040019 Backup or restore is already
running.
7A040020 Port number (XXXX) is
already in use.
7A040021 Backup folder is not empty.
Message
291
Action
If this message appears with auxiliary
code [7A041013], free disk space may
be insufficient. Ensure that there is
enough free disk space available, and
try again.
If this message appears with auxiliary
code [7A041008], a file in the
restoration folder may be in use. Check
that the file is not in use, and try again.
If this message appears with auxiliary
code [7A041015], it is possible that the
database file used in the Central Admin
Server is being used with software
other than the Central Admin Server
software. Stop using the database file
and try again.
If this message appears without
auxiliary code, the contents of the
problem are shown in the following
format.
...
Problem details
...
If this message appears frequently with
auxiliary code other than those
mentioned above, contact your
FUJITSU scanner dealer or an
authorized FUJITSU scanner service
provider.
Try again, after finishing the backup or
restoration.
Port number (XXXX) is already in use
by another application.
Change the settings of the application
using XXXX, and try restoring again.
A file or folder exists in the backup
folder.
Specify an empty folder.
If a folder which does not exist is
specified, it will be created.