As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CRUISE FLIGHT CARGO COMPARTMENT SMOKE WARNING LIGHT ILLUMINATED. CABIN CREW DID NOT SEE ANY SMOKE, BUT ACFT RETURNED TO THE AIRPORT. MX DID NOT FIND ANY TRACE OR SIGN OF SMOKE IN THE CARGO COMPARTMENT. ALL SMOKE DETECTOR WIRING WAS INSPECTED AND BOTH CARGO COMPARTMENT SMOKE DETECTORS WERE REPLACED AS A PRECAUTION & ACFT RETURNED TO SERVICE.