我最近将我的 Ubuntu-mate 18.4 更新到了 20.4。几天后，当 Ubuntu 启动时，出现了一个警告，提示它应该安装“gvfs-backends”，但是，当按下“安装”时，出现一个警告，表明这个软件可能会导致问题，并且它不是来自可靠的消息来源 。我应该怎么办？我包括请求的命令及其输出：
$ dpkg -l | grep -i gvfs
ii gvfs:amd64 1.44.1-1ubuntu1 amd64 userspace virtual filesystem - GIO module
ii gvfs-common 1.44.1-1ubuntu1 all userspace virtual filesystem - common data files
ii gvfs-daemons 1.44.1-1ubuntu1 amd64 userspace virtual filesystem - servers
ii gvfs-fuse 1.44.1-1ubuntu1 amd64 userspace virtual filesystem - fuse server
ii gvfs-libs:amd64 1.44.1-1ubuntu1 amd64 userspace virtual filesystem - private libraries
apt-cache policy gvfs-backends
gvfs-backends:
Instalados: (ninguno)
Candidato: 1.44.1-1ubuntu1
Tabla de versión:
1.44.1-1ubuntu1 500
500 http://ar.archive.ubuntu.com/ubuntu focal/main amd64 Packages
$ grep -r "^deb " /etc/apt/ --include="*.list"
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal main restricted
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal-updates main restricted
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal universe
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal-updates universe
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal multiverse
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal-updates multiverse
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu focal-security main restricted
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu focal-security universe
/etc/apt/sources.list:deb http://security.ubuntu.com/ubuntu focal-security multiverse
/etc/apt/sources.list:deb http://ar.archive.ubuntu.com/ubuntu/ focal-proposed restricted main universe multiverse
按照你的指示，我重复了一遍：
$ grep -r "^deb " /etc/apt/ --include="*.list"
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu focal main
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu focal-updates main
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu focal-backports main
/etc/apt/sources.list:deb http://archive.ubuntu.com/ubuntu focal-security main
到命令：
sudo apt-get install gvfs-backend
答案（谷歌翻译成英文）是：
Reading package list ... Done
Creating dependency tree
Reading the status information ... Done.
Do not can instal some pack. This may mean that
you asked for an impossible situation or, if you are using the distribution
unstable, that some required packages have not yet been created or have been pulled from "Incoming".
The following information can help resolve the situation:
The following packages have unmet dependencies:
gvfs-backends: Depends: libsmbclient (> = 2: 4.10.0 + dfsg) but it won't install
E: Problems could not be corrected, you have retained broken packages.
enrique@enrique-PC:~$ sudo aptitude install gvfs-backends
Se instalarán los siguiente paquetes NUEVOS:
gvfs-backends libcdio-cdda2{a} libcdio-paranoia2{a} libldb2{a}
libpython3.8{ab} libsmbclient{a} libtalloc2{a} libtevent0{a}
libwbclient0{a} python3-talloc{a} samba-libs{a}
0 paquetes actualizados, 11 nuevos instalados, 0 para eliminar y 3 sin actualizar.
Necesito descargar 7.763 kB de ficheros. Después de desempaquetar se usarán 33,8 MB.
No se satisfacen las dependencias de los siguientes paquetes:
libpython3.8 : Depende: libpython3.8-stdlib (= 3.8.10-0ubuntu1~20.04) pero 3.8.12-1+bionic1 está instalado
Las acciones siguientes resolverán estas dependencias
Mantener los paquetes siguientes en la versión actual:
1) gvfs-backends [Sin instalar]
2) libpython3.8 [Sin instalar]
3) libsmbclient [Sin instalar]
4) python3-talloc [Sin instalar]
5) samba-libs [Sin instalar]
¿Acepta esta solución? [Y/n/q/?]^C
```---------------------------------------------------------------------------------------------------------------------------------------Sep 26/2021
enrique@enrique-PC:~$ LC_ALL=C apt-cache policy libpython3.8-stdlib libpython3.8
libpython3.8-stdlib:
Installed: 3.8.12-1+bionic1
Candidate: 3.8.12-1+bionic1
Version table:
*** 3.8.12-1+bionic1 100
100 /var/lib/dpkg/status
3.8.10-0ubuntu1~20.04 500
500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
500 http://archive.ubuntu.com/ubuntu focal-security/main amd64 Packages
3.8.2-1ubuntu1 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
libpython3.8:
Installed: (none)
Candidate: 3.8.10-0ubuntu1~20.04
Version table:
3.8.10-0ubuntu1~20.04 500
500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
500 http://archive.ubuntu.com/ubuntu focal-security/main amd64 Packages
3.8.2-1ubuntu1 500
500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages
enrique@enrique-PC:~$
我听从了你最后的指示。系统没有投诉。它运行流畅，我必须说这对我来说就像黑魔法！祝贺并表示由衷的感谢！