The user is trying to upgrade to the new Junos version, which has a huge gap in between, like in this example where the user wants to upgrade from 15.1X28.3 to 18.2X75-D67.23.

1. The user is on lower junos version

labroot@jtac-mx480-r2019-re0> show version
Hostname: jtac-mx480-r2019-re0
Model: mx480
Junos: 15.1X28.3

2. He tries to validate new Junos version 18.2X75-D67.23 but it fails, throwing below error

LAB> request system software validate /var/tmp/junos-install-mx-x86-64-18.2X75-D67.23.tgz
Adding fips-mode-x86-32-20230316.184913_builder_junos_182_x75_d67 ...
Verified jail-runtime signed by PackageProductionECP256_2020
ERROR: unexpected: contents.iso
ERROR: cannot verify /packages/db/.21652.jail-runtime.tgz
.
.
Verified na-telemetry signed by PackageProductionECP256_2023
Verified oam signed by PackageProductionECP256_2020
ERROR: unexpected: contents/oamctl
ERROR: cannot verify /packages/db/.21652.oam.tgz
.
.
Mounting jfirmware-x86-32-18.2X75-D67.23
Mounting jdocs-x86-32-20230316.184913_builder_junos_182_x75_d67
Mounting fips-mode-x86-32-20230316.184913_builder_junos_182_x75_d67
chroot: pwd_mkdb: No such file or directory
Abort trap
Unable to regenerate Hardware Database, skipping hardware database checks at install time
Validating against /config/juniper.conf.gz
Abort trap
Validation failed

3. Later, he might try to upgrade to 18.2X75-D67.23. It will throw an error but will request a reboot.

LAB> request system software add /var/tmp/junos-install-mx-x86-64-18.2X75-D67.23.tgz validate    
NOTICE: Validating configuration against junos-install-mx-x86-64-18.2X75-D67.23.tgz.
NOTICE: Use the 'no-validate' option to skip this if desired.
Verified junos-install-mx-x86-64-18.2X75-D67.23 signed by PackageProductionECP256_2023
Verified manifest signed by PackageProductionECP256_2023
ERROR: unexpected: contents.iso
ERROR: cannot verify /packages/db/.60163.jail-runtime.tgz
.
.
Verified oam signed by PackageProductionECP256_2020
ERROR: unexpected: contents/oamctl
ERROR: cannot verify /packages/db/.60163.oam.tgz
Verified os-boot-junos signed by PackageProductionECP256_2020
ERROR: unexpected: contents/junos-boot.tar
ERROR: cannot verify /packages/db/.60163.os-boot-junos.tgz
Verified os-compat32 signed by PackageProductionECP256_2020
ERROR: unexpected: contents/contents.izo
ERROR: cannot verify /packages/db/.60163.os-compat32.tgz
.
.
Verified vrr-mx signed by PackageProductionECP256_2023
NOTICE: 'pending' set will be activated at next reboot...

4. All the packages were not installed, and when the user tried to reboot the router, it started throwing the below error.

LAB> request system reboot
Reboot the system ? [yes,no] (no) yes

error: Pending installation
error: shutdown aborted

1. Upgrading to new junos involves a number of factors.
2. In this case, upgrading the router from 15.1 to 18.2 has a huge gap.
3. There will be a lot of compatibility issues and a huge difference in the freebsd version.
4. It is always recommended to perform hop upgrade instead of direct upgrades.
5. In this case, I opted to go through a hop upgrade from 15.1 to 17.2 and this time it went smoothly.

LAB> request system software add junos-install-mx-x86-64-17.2X75-D103.7.tgz validate    
NOTICE: Validating configuration against junos-install-mx-x86-64-17.2X75-D103.7.tgz.
NOTICE: Use the 'no-validate' option to skip this if desired.
Verified junos-install-mx-x86-64-17.2X75-D103.7 signed by PackageProductionEc_2019
.
.
Hardware Database regeneration succeeded
Validating against /config/juniper.conf.gz
mgd: commit complete
Validation succeeded
NOTICE: 'pending' set will be activated at next reboot...


labroot@jtac-mx480-r2019-re0> request system reboot <---------- Router rebooted
Reboot the system ? [yes,no] (no) yes

*** FINAL System shutdown message from labroot@jtac-mx480-r2019-re0 ***      

System going down IMMEDIATELY

6. After rebooting the router, after a successful message, router came "UP", I could see it with Junos: 17.2

LAB>
Last login: Fri May 17 14:19:11 2024 from 10.85.228.17
--- JUNOS 17.2X75-D103.7 Kernel 64-bit  JNPR-10.3-20180615.4674357_buil

7. I upgraded the router from 17.2 to 18.2X75.D67.23 and it worked fine.

LAB> request system software add /var/tmp/junos-install-mx-x86-64-18.2X75-D67.23.tgz validate          
NOTICE: Validating configuration against junos-install-mx-x86-64-18.2X75-D67.23.tgz.
NOTICE: Use the 'no-validate' option to skip this if desired.
.
.
Mounting fips-mode-x86-32-20230316.184913_builder_junos_182_x75_d67
Hardware Database regeneration succeeded
Validating against /config/juniper.conf.gz
mgd: commit complete
Validation succeeded
NOTICE: 'pending' set will be activated at next reboot...

labroot@jtac-mx480-r2019-re0> request system reboot <---------- Router rebooted
Reboot the system ? [yes,no] (no) yes
                                                                              
*** FINAL System shutdown message from labroot@jtac-mx480-r2019-re0 ***      
System going down IMMEDIATELY                                                  
                                                                               
Shutdown NOW!
[pid 39824]

8. We can see the router came up with 18.2X75.D67.23 after rebooting.

labroot@jtac-mx480-r2019-re0> show version
Hostname: jtac-mx480-r2019-re0
Model: mx480
Junos: 18.2X75-D67.23