Ubuntu boot systemd[1]: Failed to start casper-md5check Verify Live ISO checksums

Question

When booting the laptop a message like this systemd[1]: Failed to start casper-md5check Verify Live ISO checksums. shows up (this is taken from journalctl -p err) and systemctl status casper-md5check.service shows:

× casper-md5check.service - casper-md5check Verify Live ISO checksums
     Loaded: loaded (/lib/systemd/system/casper-md5check.service; enabled; vendor preset: enabled)
     Active: failed (Result: exit-code) since Sat 2022-07-30 09:24:42 EEST; 45min ago
    Process: 787 ExecStart=/usr/lib/casper/casper-md5check /cdrom /cdrom/md5sum.txt (code=exited, status=1/FAILURE)
   Main PID: 787 (code=exited, status=1/FAILURE)
        CPU: 3ms

iul 30 09:24:42 AcerAspireV5-552G systemd[1]: Starting casper-md5check Verify Live ISO checksums...
iul 30 09:24:42 AcerAspireV5-552G casper-md5check[787]: .fopen md5_file: No such file or directory
iul 30 09:24:42 AcerAspireV5-552G casper-md5check[787]: Checking integrity, this may take some time (or try: fsck.mode=skip)
iul 30 09:24:42 AcerAspireV5-552G systemd[1]: casper-md5check.service: Main process exited, code=exited, status=1/FAILURE
iul 30 09:24:42 AcerAspireV5-552G systemd[1]: casper-md5check.service: Failed with result 'exit-code'.
iul 30 09:24:42 AcerAspireV5-552G systemd[1]: Failed to start casper-md5check Verify Live ISO checksums.

I tried running sudo /usr/lib/casper/casper-md5check /cdrom /cdrom/md5sum.txt and I get the following:

.
Checking integrity, this may take some time (or try: fsck.mode=skip)
fopen md5_file: No such file or directory

with error code 1.

EDIT 1

I disabled it from starting by running sudo systemctl disable casper-md5check.service. But that doesn't answer to how the problem appeared.

EDIT 2

contents of /etc/lsb-release

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=22.04
DISTRIB_CODENAME=jammy
DISTRIB_DESCRIPTION="Linux Lite 6.0"

Answer 1

Running systemctl --failed likely produced output similar to the following which led you to this site:

UNIT                    LOAD   ACTIVE SUB    DESCRIPTION            
● casper-md5check.service masked failed failed casper-md5check.service

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.
1 loaded units listed.

It seems this is a non-critical bug which has found itself in the Linux Mint 21 (Vanessa) world from the Ubuntu 22.04 (Jammy) repos.

$ lsb_release -a

Distributor ID: Linuxmint
Description:    Linux Mint 21
Release:    21
Codename:   vanessa

Run apt-cache show casper to show the output:

Origin: Ubuntu
Filename: pool/main/c/casper/casper_1.470_amd64.deb
Description-en: Run a "live" preinstalled system from read-only media
Description-md5: 9be0120948307c7e897a16c45a69ba0f
Tag: admin::boot, admin::filesystem, implemented-in::shell, protocol::smb,  role::plugin, scope::utility, special::completely-tagged, works-with-    format::iso9660
Task: xubuntu-live

This shows it came from the Ubuntu main repository. By the pkg description and the info gathered from the github repository file casper-md5check.c it seems to be safe to completely remove if you are not involved with anything live-boot install related. I removed the casper package with sudo apt remove casper -y

$ systemctl status casper-md5check shows that the service is masked:

× casper-md5check.service
Loaded: masked (Reason: Unit casper-md5check.service is masked.)
Active: failed (Result: exit-code) since Mon 2022-09-26 23:25:24 PDT; 7min ago
Main PID: 989 (code=exited, status=1/FAILURE)
CPU: 1ms

Sep 26 23:25:24 LT-MINT2 systemd[1]: Starting casper-md5check Verify Live ISO checksums...
Sep 26 23:25:24 LT-MINT2 casper-md5check[989]: .fopen md5_file: No such file or directory
Sep 26 23:25:24 LT-MINT2 casper-md5check[989]: Checking integrity, this may take some time (or try: fsck.mode=skip)
Sep 26 23:25:24 LT-MINT2 systemd[1]: casper-md5check.service: Main process exited, code=exited, status=1/FAILURE
Sep 26 23:25:24 LT-MINT2 systemd[1]: casper-md5check.service: Failed with result 'exit-code'.
Sep 26 23:25:24 LT-MINT2 systemd[1]: Failed to start casper-md5check Verify Live ISO checksums.

Unmasking the service with sudo systemctl unmask casper-md5check automatically removes the service unit file located at /etc/systemd/system/casper-md5check.service.

However there's still a couple more casper related files found by searching for 'casper*' that can be removed:

$ sudo rm /etc/systemd/system/casper.service
$ sudo rm /etc/systemd/system/multi-user.target.wants/casper-md5check.service
$ sudo rm /etc/systemd/system/final.target.wants/casper.service

You can then do sudo systemctl daemon-reload and sudo systemctl reset-failed in order to reset the failures.

$ systemctl --failed

UNIT LOAD ACTIVE SUB DESCRIPTION 0 loaded units listed.

$ sudo systemctl is-system-running

running