Ubuntu系统安装Laravel失败：PHP ext-dom扩展无法启用求助

错误原因 #

• phpunit/phpunit[9.5.10, ..., 9.6.x-dev] 依赖 ext-dom 扩展，但当前系统未安装或启用该扩展
• 项目根目录的composer.json要求phpunit/phpunit ^9.5.10，该需求可由上述版本范围的PHPUnit满足

解决方案 #

1. 安装并启用ext-dom扩展

• 先确认PHP CLI模式下使用的配置文件：

  php --ini
  

• 检查以下配置文件（或php --ini输出的文件）中是否启用了ext-dom，确保存在extension=dom（Linux系统可能为extension=dom.so，Windows系统需取消对应行的注释）：

  - /etc/php/7.4/cli/php.ini
  - /etc/php/7.4/cli/conf.d/10-mysqlnd.ini
  - /etc/php/7.4/cli/conf.d/10-opcache.ini
  - /etc/php/7.4/cli/conf.d/10-pdo.ini
  - /etc/php/7.4/cli/conf.d/20-calendar.ini
  - /etc/php/7.4/cli/conf.d/20-ctype.ini
  - /etc/php/7.4/cli/conf.d/20-exif.ini
  - /etc/php/7.4/cli/conf.d/20-ffi.ini
  - /etc/php/7.4/cli/conf.d/20-fileinfo.ini
  - /etc/php/7.4/cli/conf.d/20-ftp.ini
  - /etc/php/7.4/cli/conf.d/20-gettext.ini
  - /etc/php/7.4/cli/conf.d/20-iconv.ini
  - /etc/php/7.4/cli/conf.d/20-json.ini
  - /etc/php/7.4/cli/conf.d/20-mysqli.ini
  - /etc/php/7.4/cli/conf.d/20-pdo_mysql.ini
  - /etc/php/7.4/cli/conf.d/20-phar.ini
  - /etc/php/7.4/cli/conf.d/20-posix.ini
  - /etc/php/7.4/cli/conf.d/20-readline.ini
  - /etc/php/7.4/cli/conf.d/20-shmop.ini
  - /etc/php/7.4/cli/conf.d/20-sockets.ini
  - /etc/php/7.4/cli/conf.d/20-sysvmsg.ini
  - /etc/php/7.4/cli/conf.d/20-sysvsem.ini
  - /etc/php/7.4/cli/conf.d/20-sysvshm.ini
  - /etc/php/7.4/cli/conf.d/20-tokenizer.ini
  

• 根据系统安装扩展：
  • Debian/Ubuntu：sudo apt install php7.4-dom
  • CentOS/RHEL：sudo yum install php74-php-dom
  • Windows：打开PHP配置文件，取消;extension=dom行的注释（去掉分号）

2. 临时忽略扩展要求（无法启用扩展时）

运行Composer命令时添加参数跳过平台检查：

composer install --ignore-platform-req=ext-dom
# 或更新依赖时使用
composer update --ignore-platform-req=ext-dom

内容的提问来源于stack exchange，提问作者Thach Mao