From Ableton Live Forums:
We changed the folder layout of Live's library in various places, which
makes an transformation from Live 5 to Live 6 necessary. The most
prominent change in this is probably that presets has grouped by one
further level of folders below the "Presets" folder. Live 6 can't "see"
presets in a Live 5 library and v.v. The transition should be
straightforward, a number of "issues" have been reported however, with
1. The Live 6 Basics package replaces the Live 5 essential package. Part
of this replacement is that most of the Simpler presets, which came with
Live 5 are removed. Due to a small (but unluckily effective) issue with
this replacement also the samples from this presets are removed, which was
not intended (only unmodified samples and presets from the original
Essential package could have been deleted). Anyway since this is annoying,
confusing, and results in broken sets with a number of users we upload in
the next days a Live 5 Essential compatibility package, which can be
downloaded by anyone and installed using the normal "Install Live Pack"
function. It will contain the Live 5 Presets and Samples missing from the
Live 6 Basics package. (Note that simply installing the Live 5 Essential
Pack doesn't work, since it would install the Presets into different
2. When installing Live 6 for the first time Live detects whether a Library
has been installed with a previous Live 5 already. If so it requests
either to upgrade this library or to chose a different folder to install
its default packages.
Live 5 won't work with a Live 6 library. Upgrading is not reversible
however, i.e. there's no (simple) way to transform a Live 6 library back to
a Live 5 library layout. Either keep a backup of your Live 5 library if
you need or want to work parallel with Live 5, or don't take the upgrade
(by choosing a different folder).
Once upgraded no further trial for upgrade will be done automatically.
When you have chosen a new folder in the first Live won't check for upgrade
If you later want to upgrade an existing Live 5 library use the "Set
Library Path" setting in Preferences' File/Folder Pane. Once Live detects
here a Live 5 Library it will offer to upgrade that folder, too.
3. For all users who took part in the beta testing we recommend: Please
choose either a new and empty folder or a Live 5 Library, which has not
been touched by a Live 6 Beta, when installing a final Live 6.0.x version.
The upgrade mechanism should work on an hybrid Library layout, but
unexpected side effects could take place.