the installation is not being completely done. whethe the installer is crushing or installation is failed showing a message about CD or DVD problem.

[Iffat Labiba]

I am receiving two types of messages. one is "The installer encountered error copying file to the hard disk: ......" and the other "Installer crashed". I can't install Ubuntu in my vm virtualbox.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.15.10
ProcVersionSignature: Ubuntu 5.8.0-43.49~20.04.1-generic 5.8.18
Uname: Linux 5.8.0-43-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445.1
CurrentDesktop: ubuntu:GNOME
Date: Wed Jun 9 03:44:07 2021
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed initrd=/casper/initrd quiet splash --- maybe-ubiquity
LiveMediaBuild: Ubuntu 20.04.2.0 LTS "Focal Fossa" - Release amd64 (20210209.1)
ProcEnviron:
 LANGUAGE=en_US.UTF-8
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 LC_NUMERIC=C.UTF-8
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Chris Guiver (guiverc)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

Bug reporting is mostly about finding & fixing problems thus preventing future users from hitting the same bug.

I suspect a Support site would be more appropriate, eg. https://answers.launchpad.net/ubuntu. You can also find help with your problem in the support forum of your local Ubuntu community http://loco.ubuntu.com/ or asking at https://askubuntu.com or https://ubuntuforums.org, or for more support options please look at https://discourse.ubuntu.com/t/community-support/709

ps: I see numerous IO errors
Jun 8 21:34:45 ubuntu kernel: [ 21.974415] EXT4-fs warning (device sda5): ext4_clear_journal_err:5332: Filesystem error recorded from previous mount: IO failure
Jun 8 21:41:02 ubuntu kernel: [ 769.580328] FAT-fs (sda1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.

VMs if given insufficient resources can have trouble working correctly (with issues such as reading installation media (CD) one symptom), but Oracle (who own/create virtualbox) say it's a user error, not product error. Thus my support suggestion.