This server used to back up just fine, then one day it started failing and hasn't successfully backed up since!  Can you help me figure out why?

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attribSet: dir=f%2f/var/lib/xml-core exists
attribSet(dir=f%2f/var/lib/xml-core, file=xml-core, size=304, placeholder=)
attribWrite(dir=f%2f/var/lib) -> /var/lib/backuppc/pc/ares/new/f%2f/fvar/flib/attrib
attribWrite(dir=f%2f/var/lib/xml-core) -> /var/lib/backuppc/pc/ares/new/f%2f/fvar/flib/fxml-core/attrib
Can't write 33792 bytes to socket
Sending csums, cnt = 388, phase = 1
Sending empty csums for var/log/auth.log.1
attribSet: dir=f%2f/var exists
attribSet(dir=f%2f/var, file=local, size=4096, placeholder=1)
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makePath(/var/lib/backuppc/pc/ares/new//f%2f/fvar/flocal, 0777)
attribSet: dir=f%2f/var exists
attribSet(dir=f%2f/var, file=local, size=4096, placeholder=)
attribSet: dir=f%2f/var exists
attribSet(dir=f%2f/var, file=lock, size=4096, placeholder=1)
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makePath(/var/lib/backuppc/pc/ares/new//f%2f/fvar/flock, 0777)
attribSet: dir=f%2f/var exists
attribSet(dir=f%2f/var, file=lock, size=4096, placeholder=)
Starting file 125086 (var/lock/aptitude), blkCnt=0, blkSize=2048, remainder=0
var/lock/aptitude: blk=, newData=0, rxMatchBlk=0, rxMatchNext=0
MD4 /var/lib/backuppc/pc/ares/153/f%2f/fvar/flock/faptitude cache = , invalid = 
var/lock/aptitude got exact match
var/lock/aptitude got digests 144a75cca48ac2502d809a0ae9280ced vs 144a75cca48ac2502d809a0ae9280ced
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attribSet: dir=f%2f/var/lock not found
attribSet(dir=f%2f/var/lock, file=aptitude, size=0, placeholder=)
attribWrite(dir=f%2f/var/lock) -> /var/lib/backuppc/pc/ares/new/f%2f/fvar/flock/attrib
attribSet: dir=f%2f/var exists
attribSet(dir=f%2f/var, file=log, size=4096, placeholder=1)
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makePath(/var/lib/backuppc/pc/ares/new//f%2f/fvar/flog, 0777)
attribSet: dir=f%2f/var exists
attribSet(dir=f%2f/var, file=log, size=4096, placeholder=)
Starting file 125088 (var/log/acpid), blkCnt=1, blkSize=2048, remainder=1115
Done: 0 files, 0 bytes
Got fatal error during xfer (aborted by signal=PIPE)
Backup aborted by user signal
Not saving this as a partial backup since it has fewer files than the prior one (got 4 and 0 files versus 119071)