GCS_Common compilation error

I’m trying to create a new MAVLink message for AIS collision avoidance but I keep getting compilation errors in files I didn’t touch at all.
Do you have a clue why? Thank you

../../libraries/GCS_MAVLink/GCS_Common.cpp: In member function 'void GCS_MAVLINK::handle_set_mode(mavlink_message_t*)':
../../libraries/GCS_MAVLink/GCS_Common.cpp:1457:80: error: too few arguments to function 'void mavlink_msg_command_ack_send_buf(mavlink_message_t*, mavlink_channel_t, uint16_t, uint8_t, uint8_t, int32_t, uint8_t, uint8_t)'
     mavlink_msg_command_ack_send_buf(msg, chan, MAVLINK_MSG_ID_SET_MODE, result);
compilation terminated due to -Wfatal-errors.

Waf: Leaving directory `/Users/giammarco/Desktop/ArduPilot/ardupilot/build/px4-v3'
Build failed
 -> task in 'objs/GCS_MAVLink' failed (exit status 1): 
	{task 4349099736: cxx GCS_Common.cpp -> GCS_Common.cpp.0.o}
 (run with -v to display more information)

Anyone? It’s such a strange error