This article explains the likely reason for ISSU failure with error message 'no route to host"
Saving the config files ...
Pushing Junos image package to the host...
Installing /var/tmp/install-media-srx-700e-junos-23.4R2-S5.5.tgz
Extracting the package ...
total 1104988
-rw-r--r-- 1 930 930 229303707 Nov 5 01:28 junos-srxentedge-x86-64-23.4R2-S5.5-linux.tgz
-rw-r--r-- 1 930 930 902189553 Nov 5 01:29 junos-srxentedge-x86-64-23.4R2-S5.5-app.tgz
Setting up Junos host applications for installation ...
error: Cannot execute command /usr/bin/rsh -JU __juniper_private4__ 192.168.1.1 /usr/sbin/upgrade_pl1
Fail to execute roll back command
xUode0:
JSRPD exited in-service-upgrade window
node1:
error: Could not connect to node1 : No route to host
node0:
Chassis ISSU Aborted
ISSU: IDLE
[Nov 5 01:30:43]: ISSU aborted and exiting ISSU window.
The error "no route to host" may appear when the configuration did not fully load after the ISSU which would cause the FPC to not come online, and that would result in interfaces not being up. Due to this the there could be a connectivity issue between the nodes in the chassis cluster.
Steps to recover
The next step is to abort the ISSU process and then from the shell mode login into the Linux operating system using root password
root@SRX1% ssh -JU __juniper_private4__ [email protected]
[email protected]'s password:
Once logged in, issue the following command to perform the rollback
root@localhost:~# upgrade_platform -r
Exit from the Linux prompt and from the shell prompt. Then, run the upgrade command again.