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Related question: Why does integrity check fail for the 12.04.1 Alternate ISO?

I downloaded and wrote ubuntu-12.04.3-server-amd64.iso to a USB key, but when I boot from it and select "Check disc for defects", I get the error: "The ./boot/grub/efi.img file failed the MD5 checksum verification..."

I'm using OS X, so the steps for writing the ISO to the USB key are as follows:

hdiutil convert -format UDRW -o ubuntu-12.04.3-server-amd64.img ubuntu-12.04.3-server-amd64.iso
sudo dd if=ubuntu-12.04.3-server-amd64.img.dmg of=/dev/rdisk1 bs=1M
diskutil eject /dev/disk1

The MD5 for the ubuntu-12.04.3-server-amd64.iso is OK, md5 ubuntu-12.04.3-server-amd64.iso gives MD5 (ubuntu-12.04.3-server-amd64.iso) = 2cbe868812a871242cdcdd8f2fd6feb9 which is the same as the MD5 on the Ubuntu website.

Is this the same issue as the question linked above? Can I proceed OK?

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1  
Where is the ./goot/ coming from? Or did you mean ./boot/? – Thomas Ward Jan 11 '14 at 19:17
    
@ThomasW. corrected, thanks. – Douglas B. Staple Jan 11 '14 at 20:46
    
What happens if you skip the convert process and try dd the iso directly? Do you get the same result? – Elder Geek Apr 14 '15 at 14:56

The OSX format conversion process is corrupting the file. Write it directly without converting it and everything will be fine.

#NUM=2  #Maybe - check which disk device is the right one 
dd if=ubuntu-12.04.3-server-amd64.img of=/dev/rdisk$NUM bs=1m

After you do that the check should complete correctly.

Don't proceed because, even if it happens to be safe this time round, next time round it might turn out that you downloaded a hacked or corrupted image and you won't be able to tell.

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