Installation via USB-stick impossible

Here are two more posts on Ubuntuforums.org that report the same problem:

http://ubuntuforums.org/showpost.php?p=10944428&postcount=1

http://ubuntuforums.org/showpost.php?p=10977762&postcount=1

Nowadays many wish to have a server without a CD-ROM in order
to save space and electricity. Not being able to install Ubuntu server
from an USB-stick without having to resort to roundabout methods,
is definitively a drawback.

Status changed to 'Confirmed' because the bug affects multiple users.

I'm experiencing same error with Lubuntu 12.10 distributive (lubuntu-12.10-alternate-i386.iso) written to USB stick with Startup Disk Creator from Ubuntu 12.04.

As workaround in my case I found that I can mount USB flash drive partition as /cdrom and setup will continue:

1. When installer report "Try mounting the CD-ROM?" select "<No>", then "<Continue>".
2. Then in "[?] Ubuntu installer main menu" select "Execute shell", then "<Continue>".
3. Mount flash drive partition as /cdrom, in my case it was /dev/sda1:

mount /dev/sda1 /cdrom

4. Exit shell by entering

exit

5. Select "Detect and mount CD-ROM" in appeared "[?] Ubuntu installer main menu" --- installation will continue.

Thanks Vladmir. That works. The weird part is that - if you do Alt + F2 and go to the shell and follow the same steps of mounting the cdrom - they don't work. But previous steps do the trick.

Vladimir's steps do not work for me---in fact (installing 14.04), the flash partition was *already* mounted at /cdrom.

I'm also experiencing the bug : Ubuntu server 14.04.2.

Solution (that needs manual intervention) that works for me
# ALT+F2 to go to the shell, umount /media && mount /dev/sdb /cdrom
(supposing that the flash drive is /dev/sdb)

Found same problem and used same solution as Jav mentioned above

Found this problem installing 14.04-2 server from USB stick created with Startup Disk Creator. Installer mounts /dev/sdxn (the USB stick partition, in my case /dev/sdc1) to /media but the installer looks for it at /cdrom. Above solution to remount at /cdrom worked for me too. H/W is an ASRock C2550D41 w/ dual Samsung 250-G SSDs at SATA 0/1.

Same problem here when trying to installing Ubuntu 14.04.3 LTS Server x64 using the media created by both Linux Live Usb Creator and UNetbootin. After the error message appeared, I tried to mount the drive manually as suggested by Vladimir and Jav but still no success. The CD-ROM integrity check (available from the installer menu) reports that checksum of ./pool/main/m/maas/python-maas-provisioningserver_1.7.6+bzr3376-0ubuntu2~14.04.1_all.deb is invalid, altough the source ISO image seems to be correct according to SHA1 checksum.

I am testing Ubuntu Yakkety server amd64 iso: http://cdimage.ubuntu.com/ubuntu-server/daily/20160924/yakkety-server-amd64.iso. On a Virtualbox VM, you start server installation from CD ROM, after selecting keyboard layout installer starts to detect and mount CD-ROM, but fails to detect it, when asked to retry mounting the CD-ROM, if you select yes it keeps on looping asing this question, if you select no you get a "Detect and mount CD-ROM installation step failed". And cannot carry on with server installation.
I checked and the ISO image is selected as virtual optical disk file in the storage settings of the IDE controller.

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/778319

@Carla - Could you try the workaround from comment #7 and see if that helps the installation proceed?