Hi, zimoun skribis: > This issue is about the upgrade of manifest version from 3 to 4. For > references, > > > > On Mon, 03 Oct 2022 at 00:10, zimoun wrote: > >> Well, I do not know if a fix is possible. The issue is a >> backward compatibility issue. > > Ludo, what is your insight on that matter? Is it fixable? Or do we > mark the issue as ’wontfix’? David wrote: > Im on commit 729ce5f and Im running: guix time-machine > --commit=7e8e070 -- package -i hello > > and it outputs: > > guix package: error: unsupported manifest format This use case cannot be fixed: you cannot use an old Guix (one that only understood manifest version 3) to manipulate a “new” profile (manifest version 4). That’s a fundamental limitation of old software being unable to deal with new formats in general. One way to work around it is to have that old ‘guix’ operate on a fresh profile (thus it’ll be version 3): rm -f /tmp/old-stuff guix time-machine --commit=7e8e070 -- package -i hello -p /tmp/old-stuff or, better yet, to use ‘guix shell’ or ‘guix environment’: guix time-machine --commit=7e8e070 -- \ environment --ad-hoc hello -- hello I’m closing this bug. Thanks, Ludo’.