How do I program my Arduino Yun Shield when I keep getting this AVRDUDE error message?
Apparently there is no ATMega32U4 on that board but ATmega328P according to the signature 0x1e950f.

Anyway, you may have to change or add new board with correct MCU setting.

Now I can see the difference between Yun and Yun shield. Shield can be connected to any Arduino board and Yun is similar like Shield + Leonardo.

I've found board definition for Arduino UNO:

unoyun.name=Arduino Uno -- Dragino Yún
unoyun.upload.via_ssh=true

unoyun.vid.0=0x2341
unoyun.pid.0=0x0043
unoyun.vid.1=0x2341
unoyun.pid.1=0x0001
unoyun.upload.tool=avrdude
unoyun.upload.protocol=arduino
unoyun.upload.maximum_size=32256
unoyun.upload.maximum_data_size=2048
unoyun.upload.speed=57600
unoyun.upload.disable_flushing=true
unoyun.upload.use_1200bps_touch=true
unoyun.upload.wait_for_upload_port=true

unoyun.bootloader.tool=avrdude
unoyun.bootloader.low_fuses=0xff
unoyun.bootloader.high_fuses=0xde
unoyun.bootloader.extended_fuses=0x05
unoyun.bootloader.file=optiboot/optiboot_atmega328.hex
unoyun.bootloader.unlock_bits=0x3F
unoyun.bootloader.lock_bits=0x0F

unoyun.build.mcu=atmega328p
unoyun.build.f_cpu=16000000L
unoyun.build.board=AVR_YUN
unoyun.build.core=arduino
unoyun.build.variant=standard


More info about it here: https://www.arduino.cc/en/Guide/ArduinoYunShield or similar product http://wiki.dragino.com/index.php?title=Yun_Shield