error/moodle/missing moodle backup xml file

The most likely cause of this error appears when the file you are trying to restore is from a Moodle 1.9.x or earlier backup.

While both use a zip or .gz the structure of the Moodle 2.0 backup file is very different than the Moodle 1.9.x or earlier files.

It may be some time before there is a converter or alternative backup/restore available for Users to restore their v1.9.x files to a Moodle 2.0 installation.

Alternatively, if the file is a Moodle 2.x file, then it is likely the file is corrupt and the xml file structure has been damaged or lost.