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Troubleshooting Software Installation on EX Series Switches

This topic describes troubleshooting issues with software installations on EX Series switches.

Recovering from a Failed Software Upgrade on an EX Series Switch



If Junos OS loads but the CLI is not working, or if the switch has no software installed, use this recovery installation procedure to install Junos OS.


If there is already a Junos OS image on the system, you can either install the new Junos OS package in a separate partition and have both Junos OS images remain on the system, or you can wipe the disk clean before the new installation proceeds.

If there is no Junos OS image on the system, follow the instructions in Booting an EX Series Switch Using a Software Package Stored on a USB Flash Drive to get an image on the system and boot the switch.

To perform a recovery installation:

  1. Power on the switch.

    The loader script starts.

    After the message Loading /boot/defaults/loader.conf displays, you are prompted with the following:

  2. Press the space bar to enter the manual loader.

    The loader> prompt displays.

  3. Enter the following command:


    • format—Use this option to wipe the installation media before installing the software package. If you do not include this option, the system installs the new Junos OS package in a different partition from the partition used by the most recently installed Junos OS package.

    • external—Use this option to install the software package on an external medium.

    • source—Represents the name and location of the Junos OS package either on a server on the network or as a file on the USB flash drive:

      • Network address of the server and the path on the server; for example, tftp://

      • The Junos OS package on a USB device is commonly stored in the root drive as the only file; for example, file:///jinstall-ex-4200-9.4R1.5-domestic-signed.tgz

    The boot process proceeds as normal and ends with a login prompt.

Rebooting from the Inactive Partition



EX Series switches shipped with Junos OS Release 10.4R2 or earlier have Junos OS loaded on the system disk in partition 1. The first time you upgrade, the new software package is installed in partition 2. When you finish the installation and reboot, partition 2 becomes the active partition. Similarly, subsequent software packages are installed in the inactive partition, which becomes the active partition when you reboot at the end of the installation process.

On switches shipped with Release 10.4R3 and later, the same Junos OS image is loaded in each of the two root partitions, and you should copy the new software image to the alternate partition each time you upgrade.

If you performed an upgrade and rebooted, the system resets the active partition. You can use this procedure to manually boot from the inactive partition.


If you have completed the installation of the software image but have not yet rebooted, issue the request system software rollback command to return to the original software installation package.


Reboot from the inactive partition:


If you cannot access the CLI, you can reboot from the inactive partition using the following procedure from the loader script prompt:

  1. Unload and clear the interrupted boot from the active partition:

  2. Select the new (inactive) partition to boot from:

    where x is either 0 (internal) or 1 (external), and the y indicates the number of the inactive partition, either 1 or 2.

    You must include the colon (:) at the end of this command.

  3. Boot Junos OS from the inactive partition:

Freeing Disk Space for Software Installation



The software installation process requires a certain amount of unused disk space. If there is not enough space, you might receive an error message such as:


Identify and delete unnecessary files by using the request system storage cleanup command.

Installation from the Boot Loader Generates ’cannot open package’ Error



When installing a Junos OS software image from the loader prompt, a “cannot open package error” is generated:


This might be due to the IP address, gateway IP address, netmask address, or server IP address not being properly set. You can set these values either from the shell or from the u-boot prompt.

To set these values from the shell:

To set these values from the u-boot prompt, log in to a console connection, reboot, and stop at the u-boot prompt (Cntrl+c):