NOTE: SOUP is compatible with Firefox 57 / Greasemonkey 4. However, due to a known bug, installing SOUP (or any other user scripts) from GitHub may fail. Until the bug is fixed (and until GM4 stabilizes more generally) I recommend using another user script manager (such as Tampermonkey or Violentmonkey) or the stand-alone SOUP extension for Firefox instead.
NOTE 2: Tampermonkey on Chrome suffersmay suffer from a race condition that can cause some fixes that rely on early loading to fail to apply properly. To avoid this, you should either use the stand-alone SOUP Chrome extension or set Inject Mode to "Instant" in Tampermonkey preferences (in the Experimental section, only visible when Config Mode is set to "Advanced" above). Other user script managers on Chrome may also be subject to similar issues.