[rdiff-backup-users] Exception ... assert not incrp.lstat()

[Michael Born]

Dear rdiff-backup users.

After years of trouble-free rdiff-backup usage I have a big problem with
a weekly backup I started some months ago.
My OpenSUSE 13.2 64bit /home/user (ext4) has been successfully backuped
to my USB3 hdd (ext4) with enough free space on it.

Since after the 11th incremental backup I get this Exception:

Fri Aug 19 19:21:05 2016  Exception 'Path:
/run/media/miborn/WD1TB/T450s_rdiff-backup/rdiff-backup-data/long_filename_data/1.2016-07-30T16:25:41+02:00.diff.gz
Index: ('long_filename_data', '1.2016-07-30T16:25:41+02:00.diff.gz')
Data: {'acl': <rdiff_backup.eas_acls.AccessControlLists instance at
0x7eff65474050>, 'uid': 1000, 'perms': 420, 'type': 'reg', 'gname':
'users', 'ea': <rdiff_backup.eas_acls.ExtendedAttributes instance at
0x7eff65464ea8>, 'ctime': 1470554687, 'devloc': 65025L, 'uname':
'miborn', 'nlink': 1, 'gid': 100, 'mtime': 1469825388, 'atime':
1471028717, 'inode': 58597284, 'size': 62}' raised of class '<type
'exceptions.AssertionError'>':
  File "/usr/lib64/python2.7/site-packages/rdiff_backup/robust.py", line
32, in check_common_error
    try: return function(*args)
  File "/usr/lib64/python2.7/site-packages/rdiff_backup/increment.py",
line 43, in Increment
    incrp = makediff(new, mirror, incpref)
  File "/usr/lib64/python2.7/site-packages/rdiff_backup/increment.py",
line 79, in makediff
    if compress: diff = get_inc(incpref, "diff.gz")
  File "/usr/lib64/python2.7/site-packages/rdiff_backup/increment.py",
line 123, in get_inc
    assert not incrp.lstat(), incrp

(more output here: http://pastebin.com/czKdWATg )

The following doesn't work any more after the Exception.
address@hidden:~> rdiff-backup --list-increments -v9
...
Fri Aug 19 23:37:23 2016  Fatal Error: Previous backup to
/run/media/miborn/WD1TB/T450s_rdiff-backup seems to have failed.
Rerun rdiff-backup with --check-destination-dir option to revert
directory to state before unsuccessful session.

After running the --check-destination-dir command I can list the backups
(see here: http://pastebin.com/zcZq6Sbh ), but re-running (incrementing)
the backup only runs in the Exception again.

Could anybody help debugging that problem?
Is this problem known and does a solution exist?

For testing I did the following things.
1. I created a new backup (new/empty destination dir). There, the backup
finished without an error.

2. I removed the last incremental backup with the help of that script:
http://www.timedicer.co.uk/programs/help/rdiff-backup-regress.sh.php
But, the incremental backup did run into the same Exception again.

3. I used the option --exclude
/home/miborn/.kde4/share/apps/okular/docdata/ to exclude the file where
the Exception happened before. Unfortunately rdiff-backup presented me a
new error message:
File "/usr/lib64/python2.7/gzip.py", line 432, in seek
    raise IOError('Negative seek in write mode')
(longer message see here: http://pastebin.com/G64SrnVn )

4. I checked the access rights of the .xml file that was listed before
the exception and also the .diff.gz file of the backup. All rights seem
all right to me. The backup is always run as the user and the user has
write access to the USB disk.


Cheers,
Michael

PS: my command line is:
time rdiff-backup -v9 --exclude
/home/miborn/.kde4/share/apps/okular/docdata/ --exclude
/home/miborn/.cache --exclude /home/miborn/MediathekView/ --exclude
/home/miborn/mnt --exclude /home/miborn/yEd --exclude /home/miborn/mnt2
--exclude /home/miborn/Videos --exclude /home/miborn/.local/share/Trash/
--exclude /home/miborn/.local/share/Steam /home/miborn
/run/media/miborn/WD1TB/T450s_rdiff-backup