Fixing Cisco FlexFlash “Connectivity Lost” Errors

Cisco added a really cool feature to their servers a while ago called Flex Flash. Basically it allows you to use an SD card (and even in a RAID1 config) for your hypervisor as well as some other utility partitions. The problem is that with certain firmware versions ESXi will lose connection to the SD card controller. Your host wont go down (remember ESXi runs from RAM), but it will thrown an error.


Luckily Cisco Released a firmware patch in October (one week to the day after I completed the install where these screenshots came from LOL), that is supposed to fix the issue.

The firmware version that fixes the issues is 1.5.(3d)

Navigate over to and under support type UCS (if you wait a second it will list the options of which UCS server there are to pick from. In the list click on your host model, this will take you to a page where you can click Server Firmware, which will take you to the page where you can download the host upgrade utility ISO file. Make sure to get the correct ISO for your host too, as they have different ISO’s for each model.

download page

This file is a bootable linux cd that contains all of the firmware for your host. If you are remote, or just too lazy to burn the ISO and walk to the server room, load up the CIMC interface and launch the KVM console.

Next go to the Media tab and attach the ISO you just downloaded and click the “Map” check box next to it. Then reboot your server. When you see the BIOS screen press F6 to enter the boot menu. From there select the vKVM DVD option.


After selecting the vKVM DVD give it some time to boot up the HUU, once its booted it will say that it is copying Firmware and Tools, this process will take a while if you are remote using the CIMC. But eventually you will need to click I agree on the EULA and then you will see the update manager screen where you can simply click “Update All” to apply all new firmware to the server.

huu update all

Once it is complete you can reboot the host and put it back into production, and the FlexFlash “lost path” errors should be fixed…


If you are just looking for screenshots related to this error, or related to what FlexFlash looks like in general check out the gallery below.



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