When a software is added for switch upgrade using the command "request system software add", and before the rebooting the device, there is inconsistency in the output of "show version" on EX2300 and EX4300. The EX4300 doesn't show any pending upgrade information whereas the same can be seen for EX2300. The article describes the reason for this inconsistency.

Output of show version on E2300 showing pending upgrade information
 

lab@ex2300> show version 

fpc0:

--------------------------------------------------------------------------

Hostname: ex2300

Model: ex2300-48p

Junos: 18.2R3.4

Pending: 21.4R3.16 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> We can see Loaded image as pending 

JUNOS OS Kernel 32-bit [20190605.30b921f_builder_stable_11]

JUNOS OS libs [20190605.30b921f_builder_stable_11]

JUNOS OS runtime [20190605.30b921f_builder_stable_11]

Output of show version on E4300 not showing pending upgrade information

lab@ex4300> show version                                  

fpc0:

--------------------------------------------------------------------------

Hostname: ex4300

Model: ex4300-32f

Junos: 18.4R2-S7.4 

JUNOS EX Software Suite [18.4R2-S7.4]

JUNOS FIPS mode utilities [18.4R2-S7.4]

Adding the image to the device again is the only way to confirm that there is a pending software install.
 

lab@ex4300> request system software add /var/tmp/jinstall-ex-4300-21.4R3.16-signed.tgz   

There is already an install pending.

  Use the 'request system reboot' command to complete the install,

  or the 'request system software rollback' command to back it out.

The two platforms EX2300 and EX4300 have different software architecture. This is the reason for difference for show version output. EX2300 is based on freebsd11 whereas EX4300 is based on freebsd6. Hence both the software images are built differently. 

In EX2300, it uses FreeBSD11 (Occam based image). The pending info comes from freebsd11 script that provides the pending upgrade information. 

The OS used in EX4300 is legacy FreeBSD6 which is an EOL operation system. This doesn't have the script to provide us with the pending upgrade information.

Engineering team won't be able to make any further changes and the fix owing to software image differences and it will not be possible to incorporate the changes in EX4300. The major reason is the FreeBSD version on EX4300 which is freebsd6 which is not applicable for any further developments.

This is a limitation