As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE FLIGHT 2722 CREW REPORTED, RECEIVED AN AIR/GROUND FAIL MESSAGE ON EICAS AFTER TAKEOFF. RETURNED TO CLE AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND RESECURED THE CONNECTORS ON THE AIR/GROUND PROXIMITY SWITCHES. ALL OPERATIONAL CHECKS WERE GOOD.