Don't recognize backup

[RPM8]

When I try to restore a custom backup it displays:
the backup archive you specified doesn't appear to be supported by this version of GameSave Manager. Please try again.

PS: I have the latest update

[InsaneMatt]

My initial thoughts are one of three things:

1. You're trying to restore a backup made with a previous "generation" release (e.g a backup made in v1.x opened in v3.x)
2. For whatever reason, the backup archive has a missing (or damaged) 'data' file
3. The archive itself has somehow become corrupt

Typically, your backups can be opened in your favourite archiving tool (WinZip, WinRAR, 7zip, etc).
From there, you can extract the contents to their original location; the gsm_info.xml file should contain some detail as to where to restore them.

[RPM8]

It's not the first option. I extracted the backup, it had 3 folders, but only the third had content. I have more than one backup and all of them have this issue.
Thanks!