Public bug reported:
On Ubuntu 26.04, apt upgrade repeatedly hangs indefinitely in the
needrestart APT post-invoke hook after kernel upgrades. needrestart
remains blocked in n_tty_write() writing to the original pseudo-
terminal, leaving the APT shutdown inhibitor active and packages
partially configured. This has now been reproduced on multiple VMs and
bare-metal hosts. The process remained stuck for multiple hours,
including in excess of 24 hours on one bare metal installation. Killing
needrestart and the stranded APT processes followed by dpkg --configure
-a recovers the system(s). Furthermore, executing needrestart -r l
immediately produced the traditional "Pending kernel upgrade"
dialog/prompt. Please note that Tailscale SSH was used to access all
relevant machines/VMs and may have some relevance or impact, but debug
reports did not indicate it was the source of the problem. Logs are
available upon request.
1) Release version: 26.04 (server)
2) Package:
needrestart:
Installed: 3.11-1ubuntu2
Candidate: 3.11-1ubuntu2
Version table:
*** 3.11-1ubuntu2 500
500 http://us.archive.ubuntu.com/ubuntu resolute/main amd64 Packages
100 /var/lib/dpkg/status
apt:
Installed: 3.2.0
Candidate: 3.2.0
Version table:
*** 3.2.0 500
500 http://us.archive.ubuntu.com/ubuntu resolute/main amd64 Packages
100 /var/lib/dpkg/status
Linux VM-name-redacted 7.0.0-30-generic #30-Ubuntu SMP PREEMPT_DYNAMIC
Fri Jul 31 18:22:54 UTC 2026 x86_64 GNU/Linux
3) Expected behaviour: apt upgrade completes and releases the shutdown
inhibitor.
4) Actual behaviour: needrestart remains blocked writing to the TTY, leaving
apt active and packages partially configured.
5) Steps to reproduce:
a. Run apt upgrade.
b. Upgrade installs a new kernel.
c. needrestart is invoked.
d. needrestart hangs indefinitely.
Process tree:
apt
└─ apt
└─ apt-pinvoke
└─ needrestart
Observed stack:
wait_woken
n_tty_write
tty_write
vfs_write
** Affects: needrestart (Ubuntu)
Importance: Undecided
Status: New
** Attachment added: "needrestart-debug.txt"
https://bugs.launchpad.net/bugs/2164687/+attachment/5993969/+files/needrestart-debug.txt
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https://bugs.launchpad.net/bugs/2164687
Title:
needrestart hangs during apt upgrade
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