I upgraded to the new 2.5.1 yesterday, bleeding edge, that's me.
All but one of my clients got backed up.  The amanda report says:

  ambiance.med.utah.edu  sdc1      lev 1  FAILED [cannot read header: got 0 
instead of 32768]
  ambiance.med.utah.edu  sdc1      lev 1  FAILED [cannot read header: got 0 
instead of 32768]
  ambiance.med.utah.edu  sdc1      lev 1  FAILED [too many dumper retry: 
"[request failed: timeout waiting for ACK]"]
  ambiance.med.utah.edu  sdb5      lev 2  FAILED [cannot read header: got 0 
instead of 32768]
  ambiance.med.utah.edu  /         lev 0  FAILED [cannot read header: got 0 
instead of 32768]
  ambiance.med.utah.edu  sdb5      lev 2  FAILED [cannot read header: got 0 
instead of 32768]
  ambiance.med.utah.edu  sdb5      lev 2  FAILED [too many dumper retry: 
"[request failed: timeout waiting for ACK]"]
  ambiance.med.utah.edu  /         lev 0  FAILED [cannot read header: got 0 
instead of 32768]
  ambiance.med.utah.edu  /         lev 0  FAILED [too many dumper retry: 
"[request failed: timeout waiting for ACK]"]

the sendbackup debug files on the client all say:

sendbackup: time 0.054: started backup
sendbackup: time 50.042: index tee cannot write [Broken pipe]
sendbackup: time 50.042: pid 5989 finish time Tue Sep  5 20:01:43 2006

There is no firewall between the server and client.  They are both
running the latest Red Hat Linux AS.  I have these settings in my
amanda.conf:

etimeout                2400
dtimeout                1800
ctimeout                30

I've searched through the archives and found nothing, everything
worked fine with 2.4.5p1.  Ideas?

Thanks,
  Steve
-- 
Steven J. Backus                        Computer Specialist
University of Utah                      E-Mail:  steven.backus AT utah DOT edu
Biomedical Informatics                  Alternate:  backus AT math.utah DOT edu
391 Chipeta Way -- Suite D150           Office:  801.587.9308
Salt Lake City, UT 84108-1266           http://www.math.utah.edu/~backus