This document describes a rare problem & solution about Catalyst 9000 Series Switches failing to boot normally and falling into bootloader (switch:) prompt.
There are no specific requirements for this document.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Catalyst 9000 Series switches boot into bootloader prompt when stack 1+1 bit is set which means the switch is configured for StackWise-Virtual. This can be identified by looking at error below when user tries to boot the switch from the bootloader prompt.
Another way to identify this problem is by looking at STACK 1+1 bootloader variable by using "set" command in bootloader mode. To get the switch in bootloader mode, press mode button while switch starts to boot up.