An attempt is made to install Junos on an MX204, using a USB.  However, on boot the router never finds the image stored on the USB drive and thus, the installation fails.

A check of the USB confirms that it is formatted correctly with FAT32 and that the image needed, junos-vmhost-install-usb-mx-x86-64-21.4R3-S5.4.img.gz, is correcting installed.

Note that the file cannot be unzipped to the actual .img archive because the file is too large, greater than the 4Gb limit supported by FAT32.

USB install boot does not find the USB image installed on the drive.

The following steps can be used to correct the USB boot issue.  The file does not need to be uncompressed, junos-vmhost-install-usb-mx-x86-64-21.4R3-S5.4.img.gz can be used as it is.  The issue with the previous installation attempt is tied to how the file was installed on the USB.

1.  Download the .gz file from download page, e.g. junos-vmhost-install-usb-mx-x86-64-21.4R3-S5.4.img.gz

2.  Use the USB Software (Rufus Software) to burn/write the .gz file to the USB.  Do not simply copy the file

3.  Insert the USB into the router and power cycle it. 

4.  Follow the prompts on the console to load the image from the USB:

- Install vmhost and Junos software on Primary and Secondary disk [y/N]? Y 

- Reboot now? [y/N]? Y 

2023-12-23 : Article Created

2025-7-31 : Improved formatting, no other change needed

2025-8-12 : Filled in Modification History