Member Avatar for tomtetlaw

I've burned the ubuntu server installer .iso to a CD. When I try to boot from it it tells me the disk boot failure message. I know it's not the CD drive that's the problem because I get the same error on multiple computers. Is there anything I have to do besides burn the .iso to the CD to make it bootable?

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  • Latest Post Latest Post by JasonHippy

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As describes, seeing "disk boot failure" on multiple machines usually means the disc in the drive is not a proper, bootable image — not necessarily a bad drive. is right to suspect the download, but there are a few other common gotchas: the ISO may have been copied to the CD as a file (instead of burned as an image), the ISO might be larger than a standard CD (so a DVD or USB is needed), the download could be corrupt, or the BIOS/UEFI boot order may not be set to boot from the optical drive. (documentation.ubuntu.com)

Quick, concrete checks you can run before reburning: confirm the ISO size (is it >700 MB?), and verify the image integrity using SHA256 (preferred) and the published checksums/signatures. Example commands:

sha256sum ubuntu-server.iso
shasum -a 256 ubuntu-server.iso
CertUtil -hashfile ubuntu-server.iso SHA256

Compare the output to the official SHA256SUMS and verify the GPG signature when available — that tells you if the download is corrupt or tampered with. (documentation.ubuntu.com)

Check what actually ended up on the burned disc: mount the CD and list its contents. If you see many files and directories (casper, preseed, etc.), the image was written correctly; if you only see a single .iso file, the ISO was copied as data and will not boot. On Linux:

sudo mount /dev/sr0 /mnt
ls -la /mnt
sudo umount /mnt

If burned incorrectly, use your burner’s "Write image" / "Burn image" option, enable "verify after burning", use a fresh CD-R (finalized) and burn at a lower speed. Official install docs note the same image-vs-data problem and burning-as-image requirement. (wiki.ubuntu.com)

If a correctly burned CD still won't boot, switch to a USB installer (official Ubuntu tools like Startup Disk Creator on Linux or Rufus on Windows are recommended), confirm BIOS/UEFI boot settings, or test the ISO in a VM to prove it boots before burning again. Those USB/how-to pages and the official checksum verification docs show the exact recommended tools and steps. (help.ubuntu.com)

Member Avatar for JasonHippy

Burning the iso is all you should need to do.
Sounds like the iso was corrupted in some way. The ubuntu download sites usually provide an md5 checksum for all downloadable files.
After downloading a file, it's usually best to create an md5 checksum. This checksum should match the checksum provided by ubuntu. If it does not match, then the file is most likely corrupted.

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