the procedure that you have linked shows that the SW upgrade/downgrade has to be done at subpackage level. One subpackage file at a time.
This means that you have to create a directory on flash where the subpackage files will be written. Then you expand the main file (the superpackage) into the subpackage files providing the directory path you have created.
Later using the issu command you load one package per time
Just to close the loop on this question. I learned from Cisco TAC that since this model ASR router doesn't have redundant rp's it is not necessary to invoke the above commands (ie. issu, etc.) and I can use the same simple process as other routers (copy image to bootflash, modify bootvar to point to new image, wr mem, reboot).
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...