Check these
- Same Google account. Select the account that created the backup.
- The backup is outdated. If the message says the backup is outdated and cannot be restored, it was made by a much older version. Restore it on a phone with the older app version, or contact us.
- Complete file. Make sure the file finished copying and isn't damaged.
- Space and battery. A big history needs free storage and some battery.
- Try restoring only some data types (for example alarms and groups first).
Still failing?
Send a bug report from Settings > About and tell us the message you see.