[Bug 2144691] Re: dirmngr 2.4.8-2ubuntu2.1 preinst script corrupted (syntax error at line 472 in dpkg-maintscript-helper) blocks install/upgrade in Ubuntu 25.10

[tstrike]

Quick Bug Report Summary (for the developers reference)
Title (as filed):
dirmngr 2.4.8-2ubuntu2.1 preinst script corrupted (syntax error at line 472 in dpkg-maintscript-helper) blocks install/upgrade in Ubuntu 25.10
Key Symptoms (from our logs):

Consistent failure during apt install dirmngr, apt upgrade, or apt --fix-broken install:text/usr/bin/dpkg-maintscript-helper: 472: Syntax error: end of file unexpected (expecting "}")
dpkg: error processing archive ... (--unpack):
 new dirmngr package pre-installation script subprocess returned error exit status 2
Error occurs on pre-installation script (preinst) of the downloaded deb.
Also seen on post-removal and post-install scripts in cleanup.
The same pattern appeared in dependent packages (openssh-client, openssh-server, login, libreoffice-common) during troubleshooting.

Reproducibility:

Fresh or partially broken 25.10 install.
sudo apt update && sudo apt install dirmngr or sudo apt upgrade triggers it consistently.
Failed across multiple mirrors (us.archive.ubuntu.com, security.ubuntu.com, archive.ubuntu.com).

Workarounds Tried (add these to the bug if you want — shows we exhausted
options):

Renaming/removing corrupt prerm/postinst → dummy empty scripts → force-purge with --force-all.
Manual deb extraction (dpkg -x) → copy files → ldconfig.
Fake status in /var/lib/dpkg/info/dirmngr.list with Status: install ok configured.
apt-mark hold dirmngr to prevent upgrades.
Purge dependent packages (gnupg2, gpg-wks-client, etc.) to stop demand.
Cache wipe (apt clean, rm /var/lib/apt/lists/*, rm cache debs).

None permanently stop the loop when apt re-downloads the deb (e.g., during fix-broken or upgrade).
Additional Context (you can add this to the bug):

The deb file itself appears corrupted (consistent failure across mirrors).
Manual extraction works — files function normally (dirmngr --version returns 2.4.8).
Issue blocks dependency chains (gnupg2 → dirmngr, openssh-server → openssh-client/sftp-server, etc.) and normal upgrade/autoremove.
Spread to other packages (openssh, login, libreoffice-common) during troubleshooting.

Attachments (optional):

Attach a snippet from /var/log/dpkg.log showing the error.
Or just paste one full error log from our conversation.

My additional comments and observations for the Bug Report

This is a legitimate packaging bug — not user error. Multiple maintainer scripts failing in the same way across packages points to a build/upload/packaging pipeline issue in 25.10.
High impact — blocks core packages (gnupg2, openssh, login) and normal system upgrades.
Likely cause — truncated maintainer scripts during build or upload. Developers should check the build logs for gnupg2 2.4.8-2ubuntu2.1 (and openssh 1:10.0p1-5ubuntu5.1) in questing-updates.
Suggestion for devs — Re-upload corrected debs or regenerate the pool files.

** Also affects: dpkg (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/2144691

Title:
  dirmngr 2.4.8-2ubuntu2.1 preinst script corrupted (syntax error at
  line 472 in dpkg-maintscript-helper) blocks install/upgrade in Ubuntu
  25.10

Status in dpkg package in Ubuntu:
  New
Status in gnupg2 package in Ubuntu:
  New

Bug description:
  Title
  dirmngr 2.4.8-2ubuntu2.1 preinst script corrupted (syntax error at line 472 in dpkg-maintscript-helper) blocks install/upgrade in Ubuntu 25.10
  Description
  Affects: Ubuntu 25.10 (Questing Quokka)
  Package: dirmngr (source: gnupg2)
  Version: 2.4.8-2ubuntu2.1 (from questing-updates/main)
  Architecture: amd64
  Symptom
  Any attempt to install, upgrade, or fix dirmngr fails with the same error during unpack:
  text/usr/bin/dpkg-maintscript-helper: 472: Syntax error: end of file unexpected (expecting "}")
  dpkg: error processing archive .../dirmngr_2.4.8-2ubuntu2.1_amd64.deb (--unpack):
   new dirmngr package pre-installation script subprocess returned error exit status 2
  This also affects post-removal and post-install scripts in cleanup. The same pattern has appeared in dependent packages (gnupg2, gpg-wks-client) and has spread to others (openssh-client, openssh-server, login, libreoffice-common) during troubleshooting.
  Steps to Reproduce

  Fresh or partially broken Ubuntu 25.10 install
  sudo apt update && sudo apt install dirmngr
  Observe failure during the unpacking of the dirmngr deb.

  Expected
  Package installs/upgrades without script errors.
  Actual
  Preinst script fails with a syntax error. Error is consistent across mirrors (us.archive.ubuntu.com, security.ubuntu.com, archive.ubuntu.com).
  Workarounds Attempted (all temporary)

  Rename/remove corrupt prerm/postinst → create dummy empty scripts → force-purge with --force-all
  Manual deb extraction (dpkg -x) → copy files to /usr/ → ldconfig
  Fake status in /var/lib/dpkg/info/dirmngr.list with Status: install ok configured
  apt-mark hold dirmngr to prevent future upgrades
  Purge dependent packages (gnupg2, gpg-wks-client) to stop demand

  None permanently stops the loop when apt re-downloads the deb (e.g., during fix-broken, upgrade, or reinstall).
  Additional Notes

  The deb file itself appears corrupted (consistent failure across mirrors).
  Manual extraction works — files function normally (dirmngr --version returns 2.4.8).
  The issue affects the dependency chain (gnupg2 → dirmngr, etc.) and blocks normal upgrade/autoremove.

  Please investigate the build/upload process for gnupg2
  2.4.8-2ubuntu2.1 in questing-updates. This may affect other packages
  if maintscripts are broken in the pipeline.

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