Seeing "Invalid Keys" on your terminal? This article quickly covers what causes that error and the steps to troubleshoot it.

If your terminal displays the message “Invalid Keys” on screen, this indicates that the encryption keys for the device have been wiped.

This can only be reset at a key injection facility. To resolve this issue, you must return the terminal to CabCard. If you are part of a fleet, please return the terminal to your fleet manager who will be able to provide you with an alternative terminal from the buffer stock on hand. Please contact our support team if you are an independent driver. 

This is a security feature and helps to keep cardholder data, and your business, safe from attackers and cyber criminals. The terminal has detected possible tampering, and has wiped the encryption keys in order to prevent malicious use. It can also be triggered when a terminal's battery drains below a safe threshold.