In MSI upgrade, if I don't include the unmodified MSI cab in the installset, windows installer throws this error during upgrade:
Error 1334. The file '{FILE}.{GUID}' cannot be installed because the file cannot be found in cabinet file '{CABFILE}.cab'. This could indicate a network error, an error reading from the CD-ROM, or a problem with this package.
Note that, the specified cab in the error is NOT modified.