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[solved] How to upgrade the Cisco 3850 switches in Install mode step by step

This is very simple and fast procedure to upgrade the Cisco 3850 switches using the USB drive – The bin file needs to copied to the Flash on all the switches

You can confirm the mode by using the sh version  command in the switch



The MAX count of switches in the stack can go up to 9 – this is the high-end limit as of toady

There are few ways to copy the code to the switch

  1. Copy the code the traditional way by using the “copy TFTP: Flash:” command to copy the software to each switch Flash
  2. 3850 switches come with USB connector and with you can use the USB drive to copy the software

Once recommendation for using the USB drive is to format the drive with FAT32  to avoid any reading errors by switch

If the code is only copied to one of the switch only – still no worries switch will copy the code to all other switches in the stack before the upgrade

let’s confirm the version on the switch and make a note of it and if you are using a USB drive than you can copy the code by using the following code – in this case we are using “03.06.04”

“copy usbflash0:cat3k_caa-universalk9.SPA.03.07.04.E.152-2.E.bin flash”

Once the code is copied to the flash – confirm by using the show flash: command to make sure that the code was copied successfully


Now you can start the install by using the following command – 1. shows the portion where the install will install and 2.  shows the number of swicthes in the stack


The install can begin anytime and does  not require downtime – however  will require a reboot so after hours is always recommended



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