Cannot open console of container

I want to open console of container in browser directly, when I input url such as http://xx.xx.xx.xx:xx/env/1a5/infra/console?instanceId=1s1&isPopup=true
the console sometimes can be shown, but sometimes cannot be opened, the error is as the following:

What is the matter?

1s1 (or 31) is a service ID, the console only works with an instance (individual container).