Recovering from a Failed Software Upgrade on an EX-series switch


The JUNOS software loads but the CLI is not working for any reason, or if the switch has no software installed.


This recovery installation procedure can be used to recover from a failed software upgrade or if if the CLI is not working for any reason.


  1. Power on the switch. The loader script starts.
  2. After the Loading /boot/defaults/loader.conf displays, you are prompted with:

    Hit [Enter] to boot immediately, or space bar for command prompt

    Hit the space bar to enter the manual loader. The loader > prompt displays.

    1. Enter the following command:
    1. install [––format] sourceWhere:
    2. –format:  Include the ––format option if you want to wipe the internal disk before installing the software package. If you do not include this option, the system installs the new JUNOS software package in a different partition from any existing JUNOS software package.
    • source:  source represents the name and location of the JUNOS software package either on a server, on the network, or as a file on an external USB drive:
      • Network address of the server and the path on the server. For example, tftp://
      • The JUNOS package on a USB device is commonly stored in the root drive as the only file. For example, file:///jinstall-ex-9.0R1-domestic.tgz


  1. The installation proceeds as normal and ends with a login prompt.


Knowledge Base ID: KB10914

Knowledge Base ID: KB10914


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