So I needed to upgrade the IOS XE on the customer’s ASR 1002 and after copying the image from USB to Flash, I issued a standard command
boot system flash asr1000rp1-advipservicesk9.03.16.03.S.155-3.S3-ext.bin
After reloading the router I get this error:
boot: unsupported boot device "asr1000rp1-advipservicesk9.03.16.03.S.155-3.S3-ext.bin"
autoboot: boot failed, restarting…
First Google search result showed that I missed ‘bootflash:‘ before the name of the IOS image and the correct command should be
boot system flash bootflash:asr1000rp1-advipservicesk9.03.16.03.S.155-3.S3-ext.bin
Definitely need to remember this!