The fix would be to allow 'socket' protocol in "lj.so" or to remove that check entirely (even better - because I don't think "lj.so" has _ANY_ knowledge to decide whether given printer/protocol is supported or not, so it's most likely wrong half of the time, making hpcups filter exit with oh-so-informative error 48).
Not really, last checked with hplip 3.12.2.
The fix would be to allow 'socket' protocol in "lj.so" or to remove that check entirely (even better - because I don't think "lj.so" has _ANY_ knowledge to decide whether given printer/protocol is supported or not, so it's most likely wrong half of the time, making hpcups filter exit with oh-so-informative error 48).