各位好，我在Ubuntu 20.04上安装paprefs时遇到了棘手的依赖版本冲突问题，试了好几种方法都没搞定，想请大家帮忙看看怎么解决。

首先我尝试直接安装paprefs：

sudo apt install paprefs

结果弹出了依赖未满足的错误：

The following packages have unmet dependencies:
paprefs : Depends: pulseaudio-module-gsettings but it is not going to be installed
Depends: pulseaudio-module-zeroconf but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

为了排查详细原因，我加了调试参数重新执行安装命令：

sudo apt -o Debug::pkgProblemResolver=true -o Debug::Acquire::http=true install paprefs

得到的调试输出如下：

Starting pkgProblemResolver with broken count: 1
Starting 2 pkgProblemResolver with broken count: 1
Investigating (0) paprefs:amd64 < none -> 1.1-1build1 @un puN Ib >
Broken paprefs:amd64 Depends on pulseaudio-module-gsettings:amd64 < none | 1:13.99.1-1ubuntu3.8 @un uH >
Considering pulseaudio-module-gsettings:amd64 1 as a solution to paprefs:amd64 9999
Reinst Failed early because of libpulse0:amd64
Considering pulseaudio-module-gsettings:amd64 1 as a solution to paprefs:amd64 9999
Broken paprefs:amd64 Depends on pulseaudio-module-zeroconf:amd64 < none | 1:13.99.1-1ubuntu3.8 @un uH >
Considering pulseaudio-module-zeroconf:amd64 1 as a solution to paprefs:amd64 9999
Reinst Failed early because of libpulse0:amd64
Considering pulseaudio-module-zeroconf:amd64 1 as a solution to paprefs:amd64 9999

看起来问题出在pulseaudio-module-gsettings和pulseaudio-module-zeroconf这两个依赖包上，于是我尝试单独安装它们：

先安装pulseaudio-module-gsettings：

sudo apt install pulseaudio-module-gsettings

同样遇到了依赖冲突：

The following packages have unmet dependencies:
pulseaudio-module-gsettings : Depends: libpulse0 (= 1:13.99.1-1ubuntu3.8) but 1:13.99.1-1ubuntu3.13 is to be installed
Depends: pulseaudio (= 1:13.99.1-1ubuntu3.8)
E: Unable to correct problems, you have held broken packages.

再安装pulseaudio-module-zeroconf：

sudo apt install pulseaudio-module-zeroconf

还是一样的错误：

The following packages have unmet dependencies:
pulseaudio-module-zeroconf : Depends: libpulse0 (= 1:13.99.1-1ubuntu3.8) but 1:13.99.1-1ubuntu3.13 is to be installed
Depends: pulseaudio (= 1:13.99.1-1ubuntu3.8)
E: Unable to correct problems, you have held broken packages.

我查看了当前系统中已安装的libpulse0和pulseaudio版本：

apt list libpulse0 # check installed version of libpulse0

输出：

libpulse0/now 1:13.99.1-1ubuntu3.13 amd64 [installed,local]
libpulse0/focal-security 1:13.99.1-1ubuntu3.8 i386

apt list pulseaudio

输出：

pulseaudio/now 1:13.99.1-1ubuntu3.13 amd64 [installed,local]
pulseaudio/focal-security 1:13.99.1-1ubuntu3.8 i386

我感觉这应该是Ubuntu 20.04的一个bug——系统里已经安装了更新版本的libpulse0（1:13.99.1-1ubuntu3.13）和pulseaudio（1:13.99.1-1ubuntu3.13），但paprefs依赖的那两个模块却要求严格等于旧版本1:13.99.1-1ubuntu3.8的libpulse0，导致安装无法进行。

有没有大佬知道怎么解决这个问题呢？

备注：内容来源于stack exchange，提问作者Anton Samokat