Examples:

GET /p/v8/g/side-by-side/console
2018-07-24 07:25:43.236 PDT
#0 go.chromium.org/luci/milo/frontend/view_console.go:517 - frontend.ConsoleHandler()
2018-07-24 07:25:43.236 PDT
  reason: error getting console

Similar error on /p/chromium/g/chromium.infra/console.

I'm able to reproduce these by visiting:
https://ci.chromium.org/p/chromium/g/chromium.infra/console
https://ci.chromium.org/p/v8/g/side-by-side/console

This is also the error I get if I type in a bogus builder group name in an existing project:
https://ci.chromium.org/p/chromium/g/not.a.group/console