Expand all | Collapse all

Junos OS upgrade for EX switches.

Jump to Best Answer
  • 1.  Junos OS upgrade for EX switches.

    Posted 10-07-2020 04:48

    Hi all. Currently I'm in the process of upgrading EX3300/4300/4600 switches(some in virtual chassis) to new Junos OS listed in the download section.


    Most of the switches haven't been upgraded in a few years so they have out of date Junos OS on them. I was wondering if I can upgrade immediately to the latest release or do I need to use incremental updates?

    For example if I have an EX4300 virtual chassis with Junos OS 14.1X53 can I go straight to Junos OS 20.1/2 or do I need to do incremental upgrades to the release I want?


    Thanks in advance for all the help.

  • 2.  Betreff: Junos OS upgrade for EX switches.

    Posted 10-07-2020 05:22

    Hi Igor,


    there are lots of threads within the J-Net forum with the identical question. E.g. here:




    Also please check the recommended firmware page for each device, as the latest and greatest releases (currently 19.4 - 20.3) could have some stability issues:



  • 3.  Re: Junos OS upgrade for EX switches.
    Best Answer

    Posted 10-07-2020 05:39

    Hello Igor:


    You cannot upgrade skipping more than 3 mayor releases for example from version 14 over to 18 directly. For example you can follow the following upgrade path:


    • 14.1X53 to 16.X
    • 16.X to 18.X
    • 18.x to 20.X

    The other alternative, if you want to upgrade directly is with a format install:





    Take in consideration that 20.X is not a stable version for the moment. I suggest to check the following document: https://kb.juniper.net/InfoCenter/index?page=content&id=KB21476



  • 4.  Re: Junos OS upgrade for EX switches.

    Posted 10-07-2020 07:03

    Thanks to both of you for the responses. I will use the upgrade path  you suggested to the version 18.X.

  • 5.  Re: Junos OS upgrade for EX switches.

    Posted 10-07-2020 14:28

    I would suggest not skipping version 15. I think that's when FreeBSD was upgraded.

  • 6.  Re: Junos OS upgrade for EX switches.

    Posted 10-08-2020 05:26

    Last attempt - step not needed.  With direct you'll get FreeBSD upgrade as well.



  • 7.  Re: Junos OS upgrade for EX switches.

    Posted 10-08-2020 06:26

    Additional info here regarding FreeBSD upgrade (and potential need for downgrade).  This still calls out old multi-step stuff 😩. Best is to NOT use validate option or specify no-validate explicitly (I have never needed this):




    Also see this KB - https://kb.juniper.net/InfoCenter/index?page=content&id=KB31903&cat=EX4300_1&actp=LIST&showDraft=false


  • 8.  Re: Junos OS upgrade for EX switches.

    Posted 10-09-2020 04:20

    Just to be clear after all this. The upgrade path should be:


    1. upgrade to 15.1 -> this step will also upgrade FreeBSD

    2. upgrade to  17.1

    3. upgrade to 18.X -> I will go for last minor release within this major release


    Will this cover all of the potential pitfalls for upgrades?