KeyError: getpwuid(): uid not found

I have been using Back in Time for many years and appreciate the developers.

This week, I updated backintime to 1.1.7.5 on Ubuntu 14.04, because backintime could not use newer busybox on my NAS. Now I use default option of 'Add prefix to SSH commands' in 'Expert Options'. It seemed to work fine, but I can't make any new snapshots.

I found the error message KeyError: 'getpwuid(): uid not found: 10490', but I can not solve this problem. Could you please help me to solve this problem?

Thank you very much for your support.

I put the error message:

$ backintime-qt4
INFO: mount ssh: <email address hidden>:/share/homes/hoge/ on /home/hoge/.local/share/backintime/mnt/82A62966/mountpoint
INFO: Lock
INFO: Inhibit Suspend started. Reason: take snapshot
INFO: Mountpoint /home/hoge/.local/share/backintime/mnt/82A62966/mountpoint is already mounted
INFO: Take a new snapshot. Profile: 1
INFO: [qt4systrayicon] begin loop
INFO: Compare with old snapshot: 20150812-120001-667
INFO: Create hard-links
INFO: Call rsync to take the snapshot
INFO: Save config file
INFO: Save permissions
Traceback (most recent call last):
  File "/usr/share/backintime/common/snapshots.py", line 499, in get_user_name
    name = pwd.getpwuid(uid).pw_name
KeyError: 'getpwuid(): uid not found: 10490'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/share/backintime/common/backintime.py", line 617, in <module>
    start_app()
  File "/usr/share/backintime/common/backintime.py", line 382, in start_app
    args.func(args)
  File "/usr/share/backintime/common/backintime.py", line 447, in backup
    ret = take_snapshot(cfg, force)
  File "/usr/share/backintime/common/backintime.py", line 58, in take_snapshot
    ret = snapshots.Snapshots( cfg ).take_snapshot( force )
  File "/usr/share/backintime/common/snapshots.py", line 996, in take_snapshot
    ret_val, ret_error = self._take_snapshot( snapshot_id, now, include_folders )
  File "/usr/share/backintime/common/snapshots.py", line 1384, in _take_snapshot
    self._save_path_info(fileinfo, decode.remote(line.rstrip(b'\n'))[head:])
  File "/usr/share/backintime/common/snapshots.py", line 1152, in _save_path_info
    user = self.get_user_name(info.st_uid).encode('utf-8', 'replace')
  File "/usr/share/backintime/common/snapshots.py", line 502, in get_user_name
    %(uid, e.strerror),
AttributeError: 'KeyError' object has no attribute 'strerror'
INFO: [qt4systrayicon] end loop