Ran into a couple of things today and wanted to spell out (mainly for myself) what the errors really mean:
R6(config-router)#passive-interface default ISIS: can not make last active ISIS-IP interface passive
You probably have an interface explicitly configured with an “ip router isis” command.
R6(config-router)#passive-interface default %Invalid command if CLNS-only
Oddly enough this is complaining that there isn’t an interface configured for IS-IS routing. Thing is, you’ll get the previous error in many cases. I haven’t figured it out yet, because I’ll go from the second error, put an interface in “ip router isis”, and the get the first error, then take the “ip router isis” out of the interface, and then successfully make all interfaces passive by default.
Also, if you have “passive-interface default” set, entering “ip router isis” for an interface also automatically appears to put in a “no passive-interface” command for the interface in question under “router isis”.