Mars M6 of the Platform Project is ready
for download or updates, EXCEPT for Mac users.
Mac users, you must start with a fresh
download, for the new "Mac App" layout; you can not "update"
to M6, and worse,
if you so, or already have, you will
end up with a broken installation. Our apologies in advance.
But, it is "recoverable".
For details, see https://wiki.eclipse.org/Platform-releng/Issues_related_to_Mac_App_installations