I created a QEMU virtual machine intending to install Ubuntu Server 20.04. The host is a Proxmox 6.x Debian system. The virtual machine parameters are:

  • 2 CPU cores, 1 socket
  • 512 MB ram, ballooning device
  • 32GB SCSI Hard Drive, VirtIO SCSI controller
  • VirtIO ethernet device

Note: these are all the Proxmox defaults from the VM creation dialog, for a Linux 5.x guest.

Once I start the VM, an Ubuntu screen comes up. Then, the following error appears:

Initramfs unpacking failed: write error
Failed to execute /init (error -2)
Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance.

1 Answer 1


The recommended minimum RAM for an Ubuntu Server installation is 1GB.

I was able verify that using the parameters above, but with 1GB of RAM, allowed the system to boot properly.

From the comments Installation with 768MB works, too (as of 2021-01-24). After installation you can reduce the RAM assignment, the server will run fine (depending on your use-case of course) with 512MB.

  • 2
    After receiving the same initramfs write error on a 512MB VM when attempting to install Ubuntu Server 20.10, I was able to successfully complete installation in by allocating 768MB of ram to the VM.
    – phinze
    Nov 17, 2020 at 15:30

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