I was upgrading a Catalyst 3850 48 port switch from version 03.07.01E to version 16.12.07. I’ve done this upgrade quite a few times. Followed the Cisco upgrade procedures that you find online when you download your software file. I always have them open, or the command needed to start the upgrade process. Console access showed me that my switch after my reload ended up in ROMMON mode.

Introduction

Recently, I have been working to upgrade Cisco network devices, mainly routers and switches, for a client. A recent network audit identified fragmentation in the IOSes and also security advisories. As a result, all the routers and switches required upgrades and it was a good opportunity for the client to standardize the IOSes for the different type of network devices in the...