DNF新一代的RPM软件包管理器。克服了YUM包管理器的一些瓶颈，提升了包括用户体验，内存占用，依赖分析，运行速度等多方面的内容。

因为服务器环境为CentOS 7，它没有预装在 CentOS 7 中，所以需要先安装DNF。

# yum install epel-release# yum install dnf# dnf --version

一、问题：

CentOS7安装DNF后，运行dnf –-version会报以下错误：

Traceback (most recent call last):File "/usr/bin/dnf", line 57, in <module>from dnf.cli import mainFile "/usr/lib/python2.7/site-packages/dnf/__init__.py", line 30, in <module>import dnf.baseFile "/usr/lib/python2.7/site-packages/dnf/base.py", line 29, in <module>import libdnf.transactionFile "/usr/lib64/python2.7/site-packages/libdnf/__init__.py", line 3, in <module>from . import confFile "/usr/lib64/python2.7/site-packages/libdnf/conf.py", line 17, in <module>_conf = swig_import_helper()File "/usr/lib64/python2.7/site-packages/libdnf/conf.py", line 16, in swig_import_helperreturn importlib.import_module('_conf')File "/usr/lib64/python2.7/importlib/__init__.py", line 37, in import_module__import__(name)ImportError: No module named _conf

其实最主要的错误就是最后一条：ImportError: No module named _conf

二、解决办法

先升级python:

yum update python*

再安装以下软件：

yum install dnf-data dnf-plugins-core libdnf-devel libdnf python2-dnf-plugin-migrate dnf-automatic -y

再次运行dnf，就正常了。

# dnf --version4.0.9Installed: dnf-0:4.0.9.2-1.el7_6.noarch at Fri 13 Nov 2020 05:40:22 AM ESTBuilt : CentOS BuildSystem <http://bugs.centos.org> at Wed 13 Feb 2019 08:19:33 PM ESTInstalled: rpm-0:4.11.3-45.el7.x86_64 at Fri 13 Nov 2020 06:10:31 AM ESTBuilt : CentOS BuildSystem <http://bugs.centos.org> at Wed 30 Sep 2020 05:30:03 PM EST