Unhelpful SQUASHFS error messages

Thank you for taking the time to report this bug and helping to make Ubuntu better. This bug did not have a package associated with it, which is important for ensuring that it gets looked at by the proper developers. You can learn more about finding the right package at [WWW] https://wiki.ubuntu.com/Bugs/FindRightPackage . I have classified this bug as a bug in squashfs.

Did you check the md5sum of the .iso image before you burned it to a cd? Did you burn at a slow speed to help prevent write errors? I think you may have a valid point about the errors, but if the disc is corrupted, not much can be done, so detailed errors can appear. How far along in the install process were you when these errors appeared?

It seems to me that there is a problem with the cd itself, either because of a bad .iso or because of a bad burn, in which case those error messages are serving their purpose.

The disk probably had some problem. It was burned by a collegue at work, but I did not check it (though I should have). He burned it at a slow speed. I still don't rule out a DVD reader issue, however.

The messages appeared during 2 of my 5 installation attempts. Each time during the file to disk copying step. At 2 different percentage of the step (hinting strongly at some cd pb).

As for the error messages, what I suggest is just to make them more readable. As is, with such kind of messages, if you are not very computer-savvy, you will be afraid you broke something or think it does not work and drop Ubuntu (which is bad, especially when the problem is just a bad cd). I think that a minor change in those messages will make a _huge_ difference. If you search for the phrase 'SQUASHFS error", you will see numerous questions about it. This illustrates that the messages are not explicit enough.

I think that this is especially important when the problem occurs during the installation. Since Ubuntu is usually not preinstalled, the install step is critical, especially when you can't access to internet because you are in the middle of the installation...

Another issue that I did not raise in my initial report is: would it be possible for the installer itself to handle such problems? When some component encounters an issue and stalls or fails, it would be nice to have the installer itself stop and give you a retry/abort option. For this component I'm afraid it would not be that easy however (you can't just set up a timer on this kind of operation).

Thanks for the package change.

Regards.

One thing about just getting an error message like "An error occured while reading the CDROM" is that while it can tell a user that something has gone wrong, it's not very helpful. A user knows something is wrong by seeing those other errors, too.
One reason for having long, descriptive, and often cryptic errors is that they can help developers and the more experienced users actually see what is going wrong - a major benefit of using open source software. This allows people to use debugging methods and seek more in depth help with their problems in order to track down the source.

For example:
 [00123.173770] SQUASHFS error: Unable to read cache block [12345678:141e]
I believe that the left bracket number is a tick count of the kernel, the middle stuff is the error, and the right bracket number is a hexadecimal valued block number of the cd that is corrupted. While cds don't generally get fixed, we can at least see what is going on and where. Though these specifics aren't very useful to us, a developer might know what is stored around that area of the disc, and if it were a problem on their end, it can hopefully be fixed. Don't get your hopes up on this one, it appears that you just have a bad cd, either because of a corrupted image file or just a bad burn.

It is not likely that the installer can handle such errors since the disc itself is corrupted, and the best way to proceed with a corrupt installer is to just stop where it is and not risk further damage to the system. Retrying the install would not be helpful and could in fact be harmful.

Finally, with errors like that, a user can search for them on google (or their search engine of choice) and see what other people have to say about it, and thus figure out what the problem is, and possibly what to do about it. This is part of the community support that comes with open source software, and is generally not available with proprietary software.

I will leave this bug report as "Incomplete" for now, feel free to continue discussion.

I have the same issue, only it constantly appears when booting from the LiveCD (doesn't matter which disk I try to boot from, one of my own, or an official disk from Canonical). It happens constantly just after it reaches the third tick on the loading bar, or rather when it is loading SquashFS.

I've been having the same trouble with Ubuntu 8.04 trying to Install or to boot from the LiveCD. I've tried re-burning the disk 5 times (on CDs and on DVDs), tried booting using two different optical drives (one a DVD writer, the other a CD-ROM), and even upgraded my optical drive and upgraded my hard drive, all to no benefit. Any idea what might be happening/how to solve this? The one thing I haven't tried is using a different computer to burn the CD.

I've been considering this bug for awhile now, and while I don't think it's likely to be fixed, it's not my decision to make. So, I will mark this bug as Triaged and let the developers decide if/how to proceed. Thank you for reporting this bug and helping make Ubuntu better.

I have been having similar problems to those described by other users on one particular computer. It has a giga-byte 7KMP motherboard, 512Mb ram and an athlon XP2200 cpu, two pata hard drives.

I have installed 7.10 successfully on the box and it run well, however when I tried to upgrade to 8.04 i ended up with this issue. I have also downloaded and burned 8.04 and 8.10 to cd. When using these as live CD's I get hundreds of squashfs errors reported during the boot up process and the system never fully boots.

The same cd's work fine on other computers that I have and install successfully, so the cd's appear to be OK.

Indeed, I have tried other live cd's on the athlon system, mandriva, fedora, suse, sabayon, and all boot successfully. This leads me to believe that something is broken in ubuntu when using it on athlon xp systems.

I have had the same pb with burning Ubuntu Vers.8.10, 9.09 and 9.10 Live Cds as pertaining to SquashFS errors.
I have tried to burn 20-30 CDs and even gone so far as to verify the last 15 disks or so with errors at SquashFS which cropped up at about 2/3 or so of the the end of the CD verifying cycle.
And it does seem to happen to Ubuntu OS and other derivates like Mint etc.
I hope this helps and I didn't know it was an issue till late January 2010 when I first tried to burn cds and never had/seen a pb like this before.

Thanks Kevin

Twelve years later...

I'm seeing this in 22.04.1 after installing Ubuntu and after being told to remove the install media. The system can't reboot by itself and pressing Esc reveals never ending log messages:

  SQUASHFS error: Unable to read ...

Although the bug occurs at a safe time. Powering off the machine and rebooting reveals a clean install.

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/249328