Ubuntu Xenial 16.04 users who updated to receive the Meltdown and Spectre patches are reporting they are unable to boot their systems and have been forced to roll back to an earlier Linux kernel image.

The issues were reported by a large number of users on the Ubuntu forums, Ubuntu's Launchpad bug tracker, and Reddit thread. Only Ubuntu users running the Xenial 16.04 series appear to be affected.

All users who reported issues said they were unable to boot after upgrading to Ubuntu 16.04 with kernel image 4.4.0-108.

"Just did an update this morning to 4.4.0-108-generic and the boot failed to process," said Punit Patpatia, an Ubuntu user, earlier today.

"Yep - same here - did update and lockup at boot screen," added a different user on the Ubuntu forums.

Canonical, the company behind Ubuntu OS, deployed Linux kernel image 4.4.0-108 as part of a security update for Ubuntu Xenial 16.04 users, yesterday, on January 9.

According to Ubuntu Security Notice USN-3522-1 and an Ubuntu Wiki page, this was the update that delivered the Meltdown and Spectre patches.

A Canonical spokesperson was not available for comment on the issue, but two new Ubuntu 16.04 updates [1, 2] with Linux kernel image 4.4.0-109 were released two hours before this article's publication.

Some of the users who reported issues with the previous update said the new kernel build worked fine. As a last resort, rolling back to kernel image 4.4.0-104 also fixes the boot issues for affected users.

Article title updated because we used the term "bricking" incorrectly. Bleeping Computer regrets the error.