When I tested switching EKF3 to EKF2 on SITL, I noticed that disable-ekf3 option causes a compile error as shown in the below.
./Tools/autotest/sim_vehicle.py -v ArduCopter --console --disable-ekf3
I can comment out of the line to compile ArduPilot:
However, it will be great if this compile error will be fixed in ArduPilot’s master. Thanks!