pyenv fails with : ModuleNotFoundError: No module named ‘_ctypes‘ error

使用pyenv 安装 3.9.7 后，在使用过程中

这个问题在安装psycopg2的时候遇到过。

重新执行发现没有效果。

系统python3导入没有错误

 pyenv安装的python3.9.7报错

查了一下资料， 需要安装 libffi-dev, ubuntu安装命令如下：

sudo apt-get install libffi-dev

 安装报错：Unable to locate package libffi-dev

sudo apt-get install libffi-dev
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package libffi-dev

 找到问题，需要修改源， 参考地址。

https://super-unix.com/ubuntu/ubuntu-unable-to-locate-package-libffi-dev/

https://askubuntu.com/questions/626138/unable-to-locate-package-libffi-dev

使用上面方法简单的添加源以后，还是报错：Ubuntu sudo apt get update 404 Not Found 问题

与之类似，示例如下：

Err:14 http://old-releases.ubuntu.com/ubuntu focal Release                                                                        
  404  Not Found [IP: 91.189.88.247 80]
Err:15 http://ppa.launchpad.net/team-gcc-arm-embedded/ppa/ubuntu focal Release                                                    
  404  Not Found [IP: 91.189.95.85 80]
Err:16 http://old-releases.ubuntu.com/ubuntu focal-updates Release                                                           
  404  Not Found [IP: 91.189.88.247 80]
Hit:17 https://linux-clients.seafile.com/seafile-deb/focal stable InRelease                
Err:18 http://old-releases.ubuntu.com/ubuntu focal-backports Release 
  404  Not Found [IP: 91.189.88.247 80]
Err:19 http://old-releases.ubuntu.com/ubuntu focal-security Release  
  404  Not Found [IP: 91.189.88.247 80]
Ign:13 https://launchpad.net/~terry.guo/+archive/gcc-arm-embedded focal InRelease
Err:20 https://launchpad.net/~terry.guo/+archive/gcc-arm-embedded focal Release
  404  Not Found [IP: 91.189.89.222 443]

参考了回答：

20.04 - Ubuntu sudo apt get update 404 Not Found problem - Ask Ubuntuj​​​​​​​j 

将sources.list恢复程默认

deb http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ focal main restricted universe multiverse
 
deb http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ focal-updates main restricted universe multiverse
 
deb http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe multiverse
 
deb http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
#deb-src http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse
 
deb http://archive.canonical.com/ubuntu focal partner
#deb-src http://archive.canonical.com/ubuntu focal partner

重新 apt-get update 就可以了

sudo apt-get update

apt-get更新完以后

sudo apt-get install libffi-dev
 
sudo apt-get install libpq-dev python3-dev

安装成功以后

pyenv install 3.9.7

 测试成功