This KB helps to address the error log observed while upgrading QFX5100 (standalone switch) from qfx-5e (TVP image) to qfx-5 (non-TVP image).

Below error is observed while upgrading the QFX5100 switch :

root@QFX5100> request system software add /var/tmp/jinstall-host-qfx-5-21.4R3-S5.17-signed.tgz no-validate

THIS IS A SIGNED PACKAGE

ERROR: /usr/libexec/ui/downgrade: a legacy Junos installation package is required...

• Please check if it is a standalone switch or a QFX5100-only VC.
• Also, please check the if we are running TVP or non-TVP image on switch. We can check the version running on switch using "show version", if it is showing flex version/5e version, then it is running qfx-5e image.
• If we are moving from qfx-5e (non-TVP) image to qfx-5 (TVP) image, the below error could be observed :

root@QFX5100> request system software add /var/tmp/jinstall-host-qfx-5-21.4R3-S5.17-signed.tgz no-validate

THIS IS A SIGNED PACKAGE

ERROR: /usr/libexec/ui/downgrade: a legacy Junos installation package is required...

• To proceed with the upgrade (from qfx-5e to qfx-5), we need to format install the switch.
• We can use KB : KB34749 [juniper.net], to format install the switch. (https://supportportal.juniper.net/s/article/EX-QFX-Procedure-to-format-install-QFX5K-device-using-a-USB?language=en_US)

• Also, running 5e image is not recommended on QFX5100 Standalone switch and QFX5100-only VC. It is only suggested to use 5e image on mixed VC (QFX5100 and QFX5110). It is based on the architecture of the device.
• To get the JTAC/Engineering support, it is recommended to run qfx-5 (non-TVP) image on QFX5100 standalone, and VC.