因为版本过低而导致composer服务器安装扩展失败怎么呢？下面由composer教程栏目给大家介绍其升级过程！

ps : 服务器 配置

Linux VM-0-9-ubuntu 4.4.0-91-generic #114-Ubuntu SMP Tue Aug 8 11:56:56 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

1. 失败经历

安装 easyswoole 的过程中，发现无法通过 composer 安装

报错信息如下：ubuntu@VM-0-9-ubuntu:~/demo/easyswoole$ composer require easyswoole/easyswoole=3.x

./composer.json has been created

Loading composer repositories with package information

Updating dependencies (including require-dev)

Installation failed, deleting ./composer.json.

[ErrorException]

"continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"?

require [--dev] [--prefer-source] [--prefer-dist] [--no-plugins] [--no-progress] [--no-update] [--update-no-dev] [--update-with-dependencies] [--ignore-platform-reqs] [--sort-packages] [-o|--optimize-autoloader] [-a|--classmap-authoritative] [--] []..

google 一下，没有对应的错误信息。 想着先查看一下 composer 版本

发现 ： composer 版本过低，就顺便升级composer 升级了再说。ubuntu@VM-0-9-ubuntu:~/demo/easyswoole$ composer -V

Composer version @package_branch_alias_version@ (1.0.0-beta2) 2016-03-27 16:00:34

升级的过程中发现，升级失败。 老版本的 composer 不能自动升级ubuntu@VM-0-9-ubuntu:~$ composer self-update

[InvalidArgumentException]

Command "self-update" is not defined.

看来是 composer 包太低，都没有自动升级的功能

2. 下载新的 composer 包

1. 新增最新的composerwget https://dl.laravel-china.org/composer.phar -O /usr/local/bin/composer

sudo chmod a+x /usr/local/bin/composer

然后把脚本 覆盖到原来的 (通过软链)

2. 查看原来的位置

sudo mv /usr/bin/composer /tmp/

sudo ln -s /usr/local/bin/composer /usr/bin/composer

ubuntu@VM-0-9-ubuntu:~$ composer -V

Composer version 1.8.5 2019-04-09 17:46:47

3. 安装

使用 composer 安装项目