Ubuntu 21.04 desktop ISO burned to DVD takes a very long time to start

[hardhu]

The ubuntu-21.04-desktop-amd64.iso burned to a dvd fails to start live session giving a bunch of error messages like:
Failed to start Snap Daemon
Failed unmounting cdrom
Failed to start Holds Snappy daemon refresh
Failed to start Ubuntu live cd installer. failed at package install time...

And then it stops.
It is not a problem of corruption of the downloaded iso: I have checked sha256 and it is correct, and the if I burn the same iso with Rufus on an usb stick the live session starts without problems.
It is not a problem of the dvd burner or of the dvd disc, because I have successfully burned other iso images of several different distributions (Mint, Manjaro, Mx Linux) using the same burner and dvd without having issues trying them on the same pc's.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1927484/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[hardhu (qzerty)]

This is a bug in the installation process, so it is not related to a package.

[hardhu (qzerty)]

I tried again today with 21.04, by checking exactly the time spent in the live session startup. After around twelve minutes from the boot, the Ubuntu logo disappears and I start to see console messages. Between those, there is one stating
A start job is running for Snap Daemon (1min19s /1min 30s).
This seems to suggest that there is a limit time of 1min 30s for that job, and if reached then the Snap Daemon fails to start.
However, this time I wait a little more, and after around 30 minutes from the boot I could finally see the graphical interface of the live session.
So I assume that the bug can be marked as fixed, even if such a long time, especially compared with the relatively short one required when starting from usb, it doesn't appear to me as a normal behavior.

[Ian Johnson (anonymouse67)]

Can anyone share full logs from such a boot specifically the output of `journalctl --no-pager` would be really helpful in diagnosing this problem.

[Launchpad Janitor (janitor)]

[Expired for snapd (Ubuntu) because there has been no activity for 60 days.]