...
3- copy the file to the QFX and do an ISSU upgrade
request system software add /var/tmp/jinstall-host-qfx-5e-x86-64-18.3R1.9-secure-signed.tgz
request system reboot
...
request system software add /var/tmp/jinstall-host-qfx-5e-x86-64-18.3R1.9-secure-signed.tgz
request system reboot