CentOS 7系统yum与rpm报错：Failed to initialize NSS library及Python模块导入失败求助

我目前在用CentOS 7系统，也清楚它已经过时了，但之后会更换系统。最近做维护检查的时候，执行了yum update -y命令，结果SSH直接崩溃断开了连接。从那之后，yum和rpm命令都一直报错，具体错误信息如下：

error: Failed to initialize NSS library
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:

   cannot import name ts

Please install a package which provides this module, or
verify that the module is installed correctly.

It's possible that the above module doesn't match the
current version of Python, which is:
2.7.5 (default, Apr  2 2020, 13:16:51)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)]

If you cannot solve this problem yourself, please go to
the yum faq at:
  http://yum.baseurl.org/wiki/Faq

我知道网上有很多相关的讨论帖子，但看了好多都没能解决我的问题，希望能得到大家的帮助，帮我搞定这个报错！

备注：内容来源于stack exchange，提问作者Ummha