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I created a bootable USB using Startup disk creator (in ubuntu desktop 12.04 32bit), from an iso image of Ubuntu server 14.04 64 bit, when I want to boot another computer using this usb drive, The computer boots up, the installation process ok, it gets through the selecting the language, then it shows me the error that it can't mount the cd-rom to continue the installation, I tried several times with others USB devices but it shows me the same error. How can I get this work ?

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This is how i got it work.

When it gets the CD-ROM error, move the install USB stick from one port, to another USB port on your PC. Then retry.

This worked. I don't know why.

Not only that but I was reinstalling 14.04 later that night, and the CD-ROM error did not happen again. The 2nd install went without a hitch.

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I'm to confirm that the "switch USB port" trick works on my machine. Very weird... – Samuel Li Nov 6 '15 at 1:08
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Yes this worked for me too! – Jeff Atwood Nov 6 '15 at 7:15
    
Amazing fix - worked a treat with 14.04.3 server amd64 too – CᴴᵁᴮᴮʸNᴵᴺᴶᴬ Nov 11 '15 at 9:17
    
worked for me as well – sushicutta Dec 2 '15 at 13:13
    
That's very weird, worked for me too. – Judge2020 Dec 3 '15 at 13:05

Problem is that the new image isn't meant to be used with unetbootin or any of the normal USB creators.

Just use dd like:

dd if=ubuntu-14.04.2-server-amd64.iso of=/dev/sdb bs=16M

(obviously, replace /dev/sdb with the path to your USB key, but don't use any partitions (i.e. don't use /dev/sdb1, /dev/sdb2, etc -- just the whole device)

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1  
This appears to be the most correct answer and doesn't require any mucking around. – Spacen Jasset Oct 28 '15 at 15:22
    
This is what I did (in ubuntu server 15.10) but the problem still occurs. – niboshi Jan 17 at 3:44
    
Works perfectly! For OS X, use sudo dd if=ubuntu-14.04.3-server-amd64.iso of=/dev/rdiskX. Check for USB drive using diskutil list. – djule5 Jan 26 at 15:04
    
This is a nice idea, but it's useless if you don't have a existing linux install. – Fake Name Mar 23 at 2:32

http://ubuntuforums.org/showthread.php?t=2253860 has an answer.

Here are the steps that I took to get it to work

  1. When you get the error, Alt+F2 to a second console.
  2. Find out which device your USB stick is (tail -n 100 /var/log/syslog)
  3. If the device is busy, umount it (umount /dev/sd[abcdef]1)
  4. Then mount it to /cdrom (mount -t vfat /dev/sd[abcdef]1 /cdrom)
  5. Alt+F1 to get back to the install console, and try detecting again
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Thank you for your question, I tried something like this, I did Alt-F2 to open a console, I tried to mount the USB myself by the command, but it failed and show me the same error. At the end I solve this by using anther iso image !! I changed this image ubuntu-14.04.2-server-amd64.iso and used this one ubuntu-14.04.1-server-amd64.iso, and it worked like a charm using the same startup disk creator and the same USB. finally I think this is a bug in that version of ubuntu server, because I'm not the only one who get this error. – Latyyfa Mar 12 '15 at 8:22
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Thanks for saving my time! – cherio Jun 26 '15 at 16:23
    
Very good and to the point answer, thanks. – Kamyar Ghasemlou Sep 17 '15 at 12:18
    
This worked for me, however I had to exit the CD-ROM detection first by hitting "no" to stop retrying. Then, alt-f2 and mount the usb to /cdrom. Then, this is the key part, alt-f1 back and select the menu step AFTER "detect cd-rom". It skips auto detection and just keeps on going with whatever you've just mounted into /cdrom – Monkpit May 8 at 5:02

With the installation CD ubuntu-14.04.2-server-amd64.iso I ran into the same issue, for me it was as easy as running: umount /dev/sdc1

My tail -n 20 /var/log/syslog showed that the installer tried multiple times to mount /dev/sdc1 but since it was already mounted to /media that obviously failed.

With the above command I unmounted the USB-CD-Drive and the following attempt to automatically mount succeeded right away. After Alt+F2 just check what is currently mounted by issuing mount in the command prompt.

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The steps here:

  1. At the third screen (don't wait until the next screen), hit Alt+F1, Enter
  2. Type: df -h to get information where is USB flash disk located/ mounted. in eg.: "/dev/sda1" mount as "/media"
  3. Type command mount -t iso9660 /media/ubuntu.iso /cdrom -o ro,loop
  4. Then hit alt+F1 to back at main screen of installation
  5. Finish. Now you can continue your process installation as usually.

The source is here...

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up vote 2 down vote accepted

I solved this by using anther iso image !! I changed this image ubuntu-14.04.2-server-amd64.iso and used this one ubuntu-14.04.1-server-amd64.iso, and it worked like a charm using the same startup disk creator and the same USB. finally I think this is a bug in that version of ubuntu server, because I'm not the only one who get this error.

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There is no ubuntu-14.04.1-server-amd64.iso - there is a ...amd64+mac.iso which I am assuming is equivalent. I also tried the umount advice which did get me past the initial error, but then "Unable to find 'pool/main/l/linux-lts-utopic/block-modules-3.16.0-generic-di_3_10.0.40~10.04.1_‌​amd64.udeb' came up. 14.04.2 doesn't seem USB friendly at all :/ – Chris Becke May 14 '15 at 21:43

Ran into this problem as well with ubuntu-14.04.3-server-amd64.iso. Unmounting the /sda/ drive from /media and remounting it as /cdrom worked but I ran into installation error further down the line when it was trying to extract files for the install. The USB drive I was trying to install from was created with Linux Live (LILI) USB creator. I recreated the usb installer with Universal USB installer from PenDriveLinux and everything worked perfectly.

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