Sometimes an additional bootstrap upgrade is required.
It has been my experience that you tend to encounter this with older hardware or when making a major jump in IOS versions. I have seen this on 4000 series switches and Cat6k Sup II. If you run into some older hardware it is definitely a good idea to check for an updated bootstrap.
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...