$ sudo apt-get install --reinstall gnome-control-center
The following packages have unmet dependencies:
libsane : Depends: libsnmp35 (>= 5.8+dfsg) but it is not going to be installed
Recommends: sane-utils (>= 1.0.29-0ubuntu5)
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
然后我尝试安装 libsane：
$ sudo apt-get install libsane
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libsane : Depends: libsnmp35 (>= 5.8+dfsg) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
等等：
$ sudo apt-get install libsnmp35
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libsnmp35 : Depends: libsensors5 (>= 1:3.5.0) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
这个错误甚至更严重。我也尝试过：
$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
还有这个，但没有什么帮助：
$ sudo apt-get --purge remove libsane
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package 'libsane' is not installed, so not removed
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
编辑：
$ sudo apt install libsensors5
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libsensors5 : Depends: libsensors-config but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
编辑2：
$ sudo apt update
[sudo] password for morlino:
Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease
Get:2 http://archive.ubuntu.com/ubuntu focal-backports InRelease [98.3 kB]
Hit:3 http://ubuntu.mirror.vu.lt/ubuntu focal InRelease
Get:4 http://ubuntu.mirror.vu.lt/ubuntu focal-updates InRelease [107 kB]
Hit:5 http://archive.canonical.com focal InRelease
Get:6 http://ubuntu.mirror.vu.lt/ubuntu focal-backports InRelease [98.3 kB]
Get:7 http://ubuntu.mirror.vu.lt/ubuntu focal-security InRelease [107 kB]
Get:8 http://archive.ubuntu.com/ubuntu focal-security InRelease [107 kB]
Hit:9 http://archive.canonical.com/ubuntu focal InRelease
Hit:10 https://dl.winehq.org/wine-builds/ubuntu focal InRelease
Get:11 http://archive.ubuntu.com/ubuntu focal-updates InRelease [107 kB]
Get:12 http://ubuntu.mirror.vu.lt/ubuntu focal-updates/main amd64 DEP-11 Metadata [102 kB]
Get:13 http://ubuntu.mirror.vu.lt/ubuntu focal-updates/universe amd64 DEP-11 Metadata [151 kB]
Get:14 http://ubuntu.mirror.vu.lt/ubuntu focal-backports/universe amd64 DEP-11 Metadata [532 B]
Get:15 http://archive.ubuntu.com/ubuntu focal-backports/universe amd64 DEP-11 Metadata [532 B]
Get:16 http://ubuntu.mirror.vu.lt/ubuntu focal-security/main amd64 DEP-11 Metadata [18.6 kB]
Get:17 http://ubuntu.mirror.vu.lt/ubuntu focal-security/universe amd64 DEP-11 Metadata [31.6 kB]
Get:18 http://archive.ubuntu.com/ubuntu focal-security/universe amd64 DEP-11 Metadata [31.6 kB]
Get:19 http://archive.ubuntu.com/ubuntu focal-security/main amd64 DEP-11 Metadata [18.6 kB]
Get:20 http://archive.ubuntu.com/ubuntu focal-updates/universe amd64 DEP-11 Metadata [151 kB]
Get:21 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 DEP-11 Metadata [102 kB]
Fetched 1,232 kB in 2s (793 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
$ sudo apt-get install --reinstall gnome-control-center
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libsane : Depends: libsnmp35 (>= 5.8+dfsg) but it is not going to be installed
Recommends: sane-utils (>= 1.0.29-0ubuntu5)
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
编辑3：
$ sudo apt install libsensors-config
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libreoffice-nlpsolver : Depends: default-jre (>= 2:1.8) but it is not going to be installed or
java8-runtime or
jre but it is not installable
libreoffice-script-provider-bsh : Depends: default-jre (>= 2:1.8) but it is not going to be installed or
java8-runtime or
jre but it is not installable
libreoffice-script-provider-js : Depends: default-jre (>= 2:1.8) but it is not going to be installed or
java8-runtime or
jre but it is not installable
libreoffice-wiki-publisher : Depends: default-jre (>= 2:1.8) but it is not going to be installed or
java8-runtime or
jre but it is not installable
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
编辑 4：它只是越来越深入，直到它说一切都是最新版本。但仍然没有修复。也许重新安装 Ubuntu 会更容易。但我会等待另一个建议，谢谢大家
morlino@morlino:~$ sudo apt install libglx-mesa0
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libglx-mesa0 : Depends: libglapi-mesa (= 20.0.4-2ubuntu1) but 20.2~git2006100730.2c711b~oibaf~b is to be installed
Depends: libgl1-mesa-dri but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
morlino@morlino:~$ sudo apt install libglapi-mesa
Reading package lists... Done
Building dependency tree
Reading state information... Done
libglapi-mesa is already the newest version (20.2~git2006100730.2c711b~oibaf~b).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
morlino@morlino:~$ sudo apt install libgl1-mesa-dri
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libgl1-mesa-dri : Depends: libglapi-mesa (= 20.0.4-2ubuntu1) but 20.2~git2006100730.2c711b~oibaf~b is to be installed
E: Unable to correct problems, you have held broken packages.
morlino@morlino:~$ sudo apt install libglapi-mesa
Reading package lists... Done
Building dependency tree
Reading state information... Done
libglapi-mesa is already the newest version (20.2~git2006100730.2c711b~oibaf~b).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.