package proftpd-core 1.3.7a+dfsg-12 failed to install/upgrade: installed proftpd-core package post-installation script subprocess returned error exit status 1

[duplessis]

upgrade 20.10 to 21.04

ProblemType: Package
DistroRelease: Ubuntu 21.04
Package: proftpd-core 1.3.7a+dfsg-12
ProcVersionSignature: Ubuntu 5.11.0-22.23-generic 5.11.21
Uname: Linux 5.11.0-22-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu65.1
Architecture: amd64
CasperMD5CheckResult: unknown
Date: Wed Jun 23 11:04:27 2021
ErrorMessage: installed proftpd-core package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2020-05-29 (390 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
Python3Details: /usr/bin/python3.9, Python 3.9.5, python3-minimal, 3.9.4-1
PythonDetails: /usr/bin/python3.9, Python 3.9.5, unpackaged
RelatedPackageVersions:
 dpkg 1.20.9ubuntu1
 apt 2.2.3
SourcePackage: proftpd-dfsg
Title: package proftpd-core 1.3.7a+dfsg-12 failed to install/upgrade: installed proftpd-core package post-installation script subprocess returned error exit status 1
UpgradeStatus: Upgraded to hirsute on 2021-06-23 (0 days ago)

[Hilmar Preusse (hille42)]

Dépaquetage de proftpd-basic (1.3.7a+dfsg-12) sur (1.3.7a-1) ...
dpkg: avertissement: impossible de supprimer l'ancien répertoire « /var/log/proftpd » : Le dossier n'est pas vide
dpkg: avertissement: impossible de supprimer l'ancien répertoire « /etc/proftpd » : Le dossier n'est pas vide
Sélection du paquet proftpd-mod-wrap précédemment désélectionné.

Did I say, that I prefer non-localized error messages?

What is the content of /var/log/proftpd & /etc/proftpd?

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Karl Schindler (k-schindler)]

it was always the proftpd-core config problem
the following solved it for me:

sudo apt remove proftpd*
sudp apt purge proftpd*
sudo apt-get install proftpd*

sudo service proftpd start

proftpd.service - ProFTPD FTP Server
     Loaded: loaded (/lib/systemd/system/proftpd.service; enabled; vendor preset: enabled)
     Active: active (running) since Mon 2021-07-19 12:53:36 +07; 9min ago
   Main PID: 12406 (proftpd)
      Tasks: 1 (limit: 4632)
     Memory: 4.1M