Some IOS releases require a ROMMON upgrade. Following is example for Cisco 1841 Router –
1. Go into the user privileged mode
2.type, upgrade rom-monitor file usbflash0:C1841_RM2.srec.124-13r.T5
The following message will appear:
This command will result in a ‘power-on reset’ of the router!
Continue? [yes/no]:
3. Type, yes and hit enter.
Show ver and you will see it is upgraded.
