EPB = elecronic parking brake.
from page 238 of manual:
If "EPB Activation Incomplete." or "EPB Unavailable" is displayed on the multi-information display
Operate the parking brake switch. If the message does not disappear after operating the switch several times, the system may be malfunctioning. Have the vehicle inspected by any authorized Toyota retailer or Toyota authorized repairer, or any reliable repairer immediately.