An error may occur if poor Wi-Fi or Bluetooth connectivity causes an interruption in a firmware update or if the Remote Key Injection (RKI) certificates did not download correctly. 

To troubleshoot an RKI error

1. Verify the Mobile Card Reader D135 has been fully charged and the phone or tablet has Wi-Fi or cellular connectivity.
   • If needed, switch to a different Wi-Fi network or turn off Wi-Fi connection to use cellular data instead.
2. Verify the Bluetooth setting on the mobile device is on, the Mobile Card Reader D135 is within a few feet of your device, and that they are paired.
3. In MobilePOS app, tap ☰ menu, then tap Card Reader Setup.
4. Tap Remote Key Injection. The key injection may take several minutes to complete.
5. Confirm the status of the following certificates is "OK": 
   • RKIAK Certificate 
   • DA Certificate 
   • DE Certificate 
6. Tap Inject Key. You should receive a Success message once complete. If inject key fails, ensure the reader is within range and try again. 
7. Swipe up and close the MobilePOS app and then open it again to restart.
8. Pair the reader. 
9. If transactions still fail, contact Customer Support.