ISSU upgrade failed in 2Xmember Qfx5120

• The ISSU upgrade fails in Qfx5120 VC
• As per the document ISSU is support on Qfx5120 device: https://apps.juniper.net/feature-explorer/feature-info.html?fKey=3136&fn=Unified+in-service+software+upgrade+%28Unified+ISSU%29 however, in VC the ISSU will not support. ISSU is for standalone switches while NSSU will work for VCs.

root@> ...4R3-S4.1-secure-signed.tgz        

[Jul 26 18:24:09]:ISSU: Validating Image

Package signature validation successful

 PRE ISSU CHECK:

 ---------------

 PFE Status              : Online

 Member Id zero            : Valid

 VC not in mixed or fabric mode    : Valid

 Member not in single node vc     : Invalid

• The switch must not be part of a Virtual Chassis or Virtual Chassis Fabric for ISSU to proceed the ISSU supported for Dual RE devices.
• Unified ISSU takes advantage of the redundancy provided by dual Routing Engines and works in conjunction with the graceful Routing Engine switchover feature and the nonstop active routing feature.
• ISSU will function will work on a standalone device, but the SDK version must be the same for both the source and target versions. For instance, if you are upgrading the device from version 22.3 to 22.4.
• The SDK version for 22.3 is SDK Ver: 06.05.23, and for 22.4 it is SDK Ver: 06.05.26. The upgrade will fail if the SDK version is mismatch.