Error -127 when trying to upgrade System 9.1 to 9.2.1

I am trying to upgrade a Beige G3 Powermac, currently running System 9.1, to System 9.2.1 and then System 9.2.2. I have 96 MB of memory and over 5GB of free disk space. I downloaded the 9.2.1. upgrade from another machine, burned it to a CD, and then doubleclicked the 9.2.1 icon on the CD. I specified a new destination folder on my hard disk; StuffIt began decompressing 9.2.1; and then, when the decompression was finished or nearly finished, the useless error appeared:
The disk "MacOS 9.2.1 Update" cannot be used, because an error of type -127 occurred.
Successive iterations of the same procedure failed. Any suggestions?
This G3, I hope, is more hospitable to old files that I need to restore than a new machine would be.