As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF FROM DCA WITH FLAPS AT 20 DEGREES THE FLAPS FAIL CAUTION MESSAGE ILLUMINATED. THE CREW FOLLOWED THE QRH AND DIVERTED TO PHL, LANDING SAFELY. MAINTENANCE REMOVED AND REPLACED THE FLAP ELECTRONIC CONTROL UNIT IAW CRJ200 AMM 27-51-05-000(400)-801. OPERATIONAL TEST OF FLAP SYSTEM WAS GOOD. THE AIRCRAFT WAS RELEASED FOR SERVICE.