I just got prompted to download this while I was using Melodyne Editor in a session.
It's also available from your accounts.
 
Can't find what's new. Anyone know if this is the ARA2 update?

The only reference I could find to 4.2 from Ceremony only mentions compatibility with Logic Pro X. I cannot find the release notes specifically.

ARA2 is still a mystery as to how Ceremony will release it. I always assumed it would be in a major release, but no clue. It may manifest more on the DAW side with hooks into data (rather than standalone ARA2, per se), since Studio One launched a chunk of those features in version 4.

It is odd that we are 9 months after the ARA2 announcement without a clear understanding of everything.

From the web page Melodyne Studio bounced me to:
 
New in Melodyne 4.2

New functions and improvements
 
ARA in Logic: Melodyne 4.2 supports ARA integration into Apple’s new Logic Pro X 10.4.2. With ARA, transfers are no longer necessary in Logic, and Melodyne follows all changes made to the audio track.
 
The transfer path in Cakewalk/Sonar: When using the Melodyne VST3 plug-in in Cakewalk/Sonar, the transfer path is now created automatically within the current project (Cakewalk Projects / <project folder> / Melodyne / Transfers).
 
Improved interaction: Melodyne 4.2 interacts even better with Studio One and now requires Studio One Version 3.5.6 or later.
 
Additional keyboard shortcut: You can now assign a keyboard shortcut from the Preferences dialog for the command “Reseparate Notes at Starting-Point Lines” that appears in the context menu in Note Assignment Mode; the shortcut is then also available in edit mode.
 
Bug fixes
 
Fixed: In Studio One, in projects with many Melodyne clips, the generation of additional Melodyne instances (using the command “Open in Melodyne”) sometimes slowed down the program.
Fixed: In Studio One under Windows, the color of the note background used to change when you altered the zoom level.
Fixed: In Studio One, the function “Unison Spread” sometimes shifted the notes in Melodyne several octaves.
Fixed: In Studio One, use of the Note Separation Tool under certain circumstances led to a crash.
Fixed: In Studio One, the note display (the lines superimposed on the waveform) was previously not updated when notes were deleted in Melodyne.
Fixed: In Studio One, in the case of copied events, “Follow Clip Selection in the DAW” resulted in the wrong bars being shown.
Fixed: In Cakewalk/Sonar, the export of a 16-bit audio file edited with Melodyne sometimes led to a crash.
Fixed: In Cakewalk/Sonar, use of the Freeze function sometimes led to a crash.
Fixed: In all DAWs with ARA, changes to the key or scale were previously not saved.
Fixed: In all DAWs with ARA, use of the Compare switch stopped local playback in Melodyne.
Fixed: In Logic 10.3, the opening of some projects with Melodyne could lead to a crash.
Fixed: In Digital Performer, the opening of projects previously edited with Melodyne sometimes led to a crash.
Fixed: In the plug-in, the command “Restore File to Original State” could under certain circumstances result in the wrong notes being deleted.
Fixed: Canceling a transfer could lead to a display error or even (if you proceeded with editing ) to the DAW crashing.
Fixed: In the plug-in, the assignable keyboard shortcut “Repeat Last Menu Action” did not work.
Fixed: If the Scale Window was open when you switched from edit mode to Note Assignment Mode, the wrong area of the timeline used to be displayed.
Fixed: In the Sound Editor, no peak values were displayed for the spectrum when Note Assignment Mode was active.
Fixed: In Melodyne studio’s track list, the “Edit” and “Reference” buttons could both be activated by Alt-clicking.
Fixed: In Melodyne studio, when multiple tracks were copied simultaneously, their contents were sometimes swapped.
Fixed: In Melodyne essential, the assignable keyboard shortcut for “Separate Notes as Trills” was missing.
Fixed: In Melodyne essential, opening a document saved by Melodyne studio sometimes resulted in the wrong track being displayed.
Fixed: In the stand-alone application, it was impossible to copy and paste notes in Tempo Assignment Mode.
Fixed: In the stand-alone application, a new detection sometimes led to the audio being offset in the timeline.
Fixed: In the stand-alone application under macOS Version 10.12, crashes sometimes occurred when the import audio function was used.

Hope everyone keeps their old installers.

Yippee, at last, the "freeze crash" problem fixed - I hope so anyway, as with me it happened EVERY-TIME!!!
Nigel
 

Downloaded, installed, put on track, adjusted some bits, froze.....then saved and it DID NOT CRASH - result - that's the first time in years the freeze /  save function has worked for me - I might use it a bit more now...perhaps - I've got so used to it not working I hardly ever use it!!
Nigel
 
 

I'll hold off a bit, let somebody else find any new bugs.
 
Being an early implementer starting with 1.0, I have a long-established routine that has let me avoid most Melodyne issues over the years: edit small sections, do the edits and then bounce, and never save a project with pending edits.
 
It's great that temporary files will now be stored with the project files, but my process doesn't require it. By the time I close a project, they're gone anyway. I don't freeze vocal tracks until all Melodyne editing has been completed. I don't use Melodyne in standalone mode, and I don't use Studio One. So there's nothing in this release that I can't live without for awhile.

My DAW PC has just decided not to boot (not even getting into BIOS) so I guess I will be fault finding rather than trying out Melodyne! The cheapskates who built the PC decided to save a couple of cents on a beep code speaker so the first job is to get hold of one. 

Sorry to hear of your current issues.
Thanks for notice of update.

Thanks TS. Such are the joys of PC ownership.