Anonable's Secret

This is a cryptic message from Anonable dating back a while. So far, no one has been able to solve it. If you can solve it, the Squard will reward you. Show your workings!

"U8GYDRBH JI NKMJTHIJ GNSFUJ ~ LOGEFTLE"

There is another message, in vigenere, that reads:

m  m  d  w  h  j  f  . r  m  z  n  s  j  '  n  x  o  g  t  f  v  b  x  q  y  a  h  q h  b  n  u  y  f  m  q h  s  k  o  p  u  f  d h  i  g  z.

We have not found the key for this message and we will reward you (but less) for finding the key.