Problems restoring a backup

I am trying to migrate from one server (Webmin 1.585, Virtualmin 3.92.gpl GPL) to another (Webmin 1.590, Virtualmin 3.92.gpl GPL). I created backups on the first server from within Virtualmin and had it FTP them to the second server. I got the message “13 servers backed up successfully, 0 had errors. 7 Virtualmin configuration settings backed up successfully.”

On the new server, when I try to restore them, I select the directory that all the backup files are in and click on “Show what will be restored”. Step two shows all of the domains and a list of things that will be restored, however when I click on the “restore now” button at the bottom of that page, I get the following error from every domain I try to restore:

"Starting restore of 13 domains from local file /virtualmin_backups/12-07-09 ..

Extracting backup archive files …

… extraction of /virtualmin_backups/12-07-09/ failed :

sh: -c: not found

/bin/tar: This does not look like a tar archive

/bin/tar: Exiting with failure status due to previous errors

… failed! See the progress output above for the reason why."

I can see that this is, indeed, an existing file, and I can open it and view all of the contents using my file manager connecting over FTP. All of the files have the following permissions:

-rw-r–r-- 1 root root

How can I debug this error message?

OK, turns out this was 2 errors in 1, and I managed to fix both.

1st error:
bzip2 was not installed on my system. get_bunzip2_command() from /usr/share/webmin/virtual-server/ should return some sort of meaningful error if bunzip2 does not exist on the system.

Which brings me to my 2nd error:
Installing bzip2 by apt, I then received the following at the console:

“… extraction of /virtualmin_backups/12-07-09/ failed : bunzip2: Bad flag `-c/bin/bunzip2’
bzip2, a block-sorting file compressor. Version 1.0.5, 10-Dec-2007.”

In the same file as above, line 2249 should have a space after the c (and maybe 1455 as well?):

$cf == 3 ? &get_bunzip2_command()." -c " :

Editing this, I am able to restore the backup files both by command line and within Virtualmin.