As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL390 FLAP UP, L/E SLAT ASYMMETRICAL EICAS MSG AND L/E CAUTION LIGHT. CYCLING ALTN L/E SLAT SWITCH HAD NO EFFECT. PERFORMED 20 DEGREE FLAP LANDING PER PILOTS OPS MANUAL. LIGHT AND MSG EXTINGUISHED ON TAXI IN WITH FLAPS UP AND BOTH CAME BACK ON AT GATE. REPLACED ALL 3 FSEU COMPUTERS. ALSO, REPLACED BOTH SLAT SWITCHES. CYCLED FLAPS SEVERAL TIMES AND OPS NORMAL.