This can happen if the previous download was somewhat interrupted and hence got corrupted.
To fix this, please purge the BCWF database and redownload a fresh copy.
From the CLI, please do the following.
Blue Coat SG210 Series#(config)content-filter
Blue Coat SG210 Series#(config content-filter)provider bluecoat disable
ok
Blue Coat SG210 Series#(config content-filter)bluecoat
Blue Coat SG210 Series#(config bluecoat)purge
ok
Blue Coat SG210 Series#(config bluecoat)exit
Blue Coat SG210 Series#(config content-filter)provider bluecoat enable
Warning: no database available.
Blue Coat SG210 Series#(config content-filter)bluecoat
Blue Coat SG210 Series#(config bluecoat)download get-now
This may take a few minutes. Please wait...
loading database......