As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT OF PIT, THE CREW REPORTED RECEIVING A LG AIR/GND FAIL MESSAGE ON THE EICAS AND THAT THE GEAR WOULD NOT RETRACT. MAINTENANCE REMOVED AND REPLACED THE RT FWD MAIN GEAR AIR/GND PROXIMITY SWITCH TARGET. SUBSEQUENT GEAR EXTENSION AND RETRACTION CHECK PROVED A GOOD FIX AT THAT TIME.