When droopy is started using unicode characters in directory path or message, it fails. The server stays up, but in terminal I get error, "UnicodeDecodeError: 'ascii' codec can't decode byte 0xce in position 18: ordinal not in range(128)". (Position differs of course). On the browser "Unable to connect" message, telnet localhost 8888 connects.
I've tested it on Debian Buster Linux.
Both of them fail (using greek characters in the example):
droopy -d /home/user -m "Το μήνυμα - unicode" 8888
droopy -d /home/κάποιοςUnicode -m "message" 8888