Meaning of "failed verification -- update retained (will try again)."

[Peng Yu]

Hi,

I see some warnings like the following. Could anybody explains what
they mean? Thanks.

19/31274477.pdf
    257,169,119   0%    1.26MB/s    0:03:15 (xfr#121,
to-chk=848309/1043298)WARNING: 18/32281577.pdf failed verification --
update retained (will try again).
WARNING: 19/28879866.pdf failed verification -- update retained (will
try again).

-- 
Regards,
Peng