Can't start tftpd because port is already in use by launchd
These steps solved my problem


Reload plist

sudo launchctl unload -F /System/Library/LaunchDaemons/tftp.plist
sudo launchctl load -F /System/Library/LaunchDaemons/tftp.plist

(Re)enable service

sudo launchctl disable system/com.apple.tftpd
sudo launchctl enable system/com.apple.tftpd

Start service (or restart)

sudo launchctl start com.apple.tftpd



Thank you everyone who participated in discussion, especially @Prado