As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED DURING APPROACH WITH FLAPS SELECTED AT 20 DEGREES, RECEIVED "LEADING EDGE" ANNUNCIATOR AND "LEADING EDGE ASSYMETRY" EICAS MESSAGE. EMERGENCY DECLARED LANDED WITHOUT INCIDENT. REPLACED FLAP SLAT ELECTRONIC UNIT THAT HAD FAULTED. SYSTEM GROUND CHECKED NORMAL OPERATION.