I have run into the exact same problem on a client that is running
Debian (Etch) linux using tar version 1.15.91 (and amanda 2.5.0p2-1).
I have now noticed, given your message, that things worked fine with
the first Debian tar 1.15.91 package but, when a revised tar 1.15.91
package was released end of July, 2 of the 3 partitions on the client
began failing during the size estimation stage with the same tar
error message, "Unexpected field value".

I'm going to force a full level backup of all partitions using the new
tar release yet, if this or the following level 1 fails (given what
Olivier said), I will try downgrading to the previous package
similarly.

Paul

->>In response to your message<<-
  --received from McGraw, Robert P.--
>
> It seems that tar 1.15.91 does not work with my version of amanda. I have
> dropped back to an older version of tar until I can upgrade my amanda.
> 
> Thanks
> 
> Robert
> 
> 
> _____________________________________________________________________
> Robert P. McGraw, Jr.
> Manager, Computer System                 EMAIL: rmcgraw AT purdue DOT edu
> Purdue University                         ROOM: MATH-807
> Department of Mathematics                PHONE: (765) 494-6055
> 150 N. University Street                   FAX: (419) 821-0540
> West Lafayette, IN 47907-2067            
> 
> 
> > -----Original Message-----
> > From: Olivier Nicole [mailto:on AT cs.ait.ac DOT th]
> > Sent: Friday, September 08, 2006 10:37 AM
> > To: McGraw, Robert P.
> > Cc: amanda-users AT amanda DOT org
> > Subject: Re: Amanda error "Unexpected field value..."
> > 
> > 
> > > The difference is that the good run was a level 0 and the run with the
> > error
> > > was a level 1.
> > > What is the "Unexpected field value"?
> > 
> > Well that's the problem with cygwin... We have little reference.
> > 
> > Apparently running level 0 gtar creates a sort of index file, to use
> > in level 1 and compare files that have changed.
> > 
> > And it seems that in between the run 0 and 1 gtar cannot read the file
> > it created.
> > 
> > If you look at the sendzie debug you should see a command very close
> > to this one
> > 
> > gtar --create --file - --directory /local
> > --one-file-system --listed-incremental /local/Amanda/amanda-2.4
> > .5p1/var/amanda/gnutar-lists/coriolis_local_1.new --sparse
> > --ignore-failed-read --totals .
> > 
> > but that will say "gtar --create --file /dev/null ..."
> > 
> > Did that one completed without error?
> > 
> > Try to run the long gtar command by hand, with --file - and --file
> > /dev/null
> > 
> > Tryto extract the comamnd for level 0 and run it...
> > 
> > Check your version of gtar.
> > 
> > Bests,
> > 
> > Olivier



-- 
Paul Yeatman       (858) 534-9896        pyeatman AT ucsd DOT edu
             ==================================
             ==Proudly brought to you by Mutt==
             ==================================