...
>Unexpected error from lstat, errno = 22
...

The lstat() function is for acquiring information on symbolic links
and its varying argument is the name of that file system object, and
22 suggests EINVAL, which in turn suggests a wacky object (symlink) name.

I'd recommend examining the backup log to identify the region of the
file system where the backup failed, and then look around there for
a bogus symlink.  Whomever put it there may be prone to do such again,
so might need some education.

  Richard Sims  http://people.bu.edu/rbs