unavailable

Most of the time, talk about the actions that customers should take rather than describing UI.

When you must discuss UI, use not available or isn’t available instead of unavailable, disabled, or grayed to describe commands and options that are in an unusable state. Use appears dimmed if you must describe their appearance. It’s OK to use unavailable to describe an outage or a service that isn’t offered to certain customers.

Examples
The command isn’t available until you select text.
If the option appears dimmed, it's not available.
If the command prompt isn’t available, your network administrator might have turned off this feature.
Some My Site features are temporarily unavailable. Please try again later.

See also disable, disabled, turn on, turn off