Ubuntu 18 → 22 升级实录

升级的原因是因为要回国呆一段时间，想装个wireguard 搞下VPN。但是wireguard的自动化脚本不支持旧版的ubuntu所以就开始着手升级。（话说18也是够老的了。。。）

升级前的准备

备份文件

tar -czvf wordpress_files_backup.tar.gz /var/www/html

tar -czvf wordpress_files_backup.tar.gz /var/www/html

Bash

备份数据库

mysqldump -u user -p db > wordpress_db_backup.sql

mysqldump -u user -p db > wordpress_db_backup.sql

Bash

1️⃣ 第一阶段：18.04 → 20.04

sudo do-release-upgrade

sudo do-release-upgrade

Bash

执行上面指令直接完成升级

2️⃣ 第二阶段：20.04 → 22.04

sudo do-release-upgrade

sudo do-release-upgrade

Bash

这次执行完之后报下面错误

ModuleNotFoundError: No module named 'apt_pkg'

ModuleNotFoundError: No module named 'apt_pkg'

Bash

似乎是系统在用手动安装的 Python（3.9）而apt 依赖系统 Python（3.8）

which python3
// output /usr/local/bin/python3

which python3
// output /usr/local/bin/python3

Bash

搜了一下Stackoverflow下面指令可以修复

sudo apt install --reinstall python3 python python3-minimal --fix-broken

sudo apt install --reinstall python3 python python3-minimal --fix-broken

Bash

但是chatgpt说即使这样可以运行，但因为路径不对以后会有隐患，所以还是把路径给修复了

sudo mv /usr/local/bin/python3 /usr/local/bin/python3.bak

sudo mv /usr/local/bin/python3 /usr/local/bin/python3.bak

Bash

然后用下面代码执行了一下发现了另外一个错误

python3 -c "import apt_pkg"
//报错 /usr/local/bin/python3: No such file or directory

python3 -c "import apt_pkg"
//报错 /usr/local/bin/python3: No such file or directory

Bash

hash -r

hash -r

Bash

重新清理了一下bash的缓存就可以了

再次尝试 sudo do-release-upgrade出现下面错误

Checking for a new Ubuntu release
Please install all available updates for your release before upgrading.

Checking for a new Ubuntu release
Please install all available updates for your release before upgrading.

Bash

所以必须提前把apt的package都更新一下

sudo apt update
sudo apt upgrade -y
sudo apt dist-upgrade -y
sudo apt autoremove -y

sudo apt update
sudo apt upgrade -y
sudo apt dist-upgrade -y
sudo apt autoremove -y

Bash

再次尝试 sudo do-release-upgrade

这次总算成功升级了！

升级后需要reboot一下然后等待服务器重启完成后就可以继续ssh到VPS里了。升级后发现 WordPress 挂掉了，基本上升级就是会这样。。。现象为网站 500 / Service Unavailable

应该是服务器没问题但是后端php出了问题。

先确认 PHP和php fpm发现8.1的fpm不存在。

php -v
// PHP 8.1.2-1ubuntu2.23 (cli) (built: Jan 7 2026 08:37:41) (NTS) Copyright (c) The PHP Group Zend Engine v4.1.2, Copyright (c) Zend Technologies with Zend OPcache v8.1.2-1ubuntu2.23, Copyright (c), by Zend Technologies 
systemctl status php8.1-fpm
// Unit php8.1-fpm.service could not be found.

php -v
// PHP 8.1.2-1ubuntu2.23 (cli) (built: Jan 7 2026 08:37:41) (NTS) Copyright (c) The PHP Group Zend Engine v4.1.2, Copyright (c) Zend Technologies with Zend OPcache v8.1.2-1ubuntu2.23, Copyright (c), by Zend Technologies 
systemctl status php8.1-fpm
// Unit php8.1-fpm.service could not be found.

Bash

我们需要安装一下然后再起动

sudo apt install php8.1-fpm
sudo systemctl start php8.1-fpm

sudo apt install php8.1-fpm
sudo systemctl start php8.1-fpm

Bash

安装后按照提示在apache2里启动它

sudo a2enmod proxy_fcgi setenvif
sudo a2enconf php8.1-fpm
sudo systemctl restart apache2

sudo a2enmod proxy_fcgi setenvif
sudo a2enconf php8.1-fpm
sudo systemctl restart apache2

Bash

再次打开网站，WordPress 恢复正常

Ubuntu 18 → 22 升级实录

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