问题

本博客使用Laravel作为基础框架搭建，在多方对比Sitemap插件后，最后选择laravelium/sitemap作为SiteMap基础插件。
https://github.com/Laravelium/laravel-sitemap
然而在使用Composer引入laravelium/sitemap拓展包时，并不像github中描述的这般顺利。
国内镜像提示没有找到任何版本的安装包。
Could not find a matching version of package laravelium/sitemap.

解决方式

切换Composer镜像源为国际镜像或者取消镜像
在这里，我选择的是直接取消镜像 composer config -g --unset repos.packagist
然后翻墙使用 composer require laravelium/sitemap 或者 composer update 引入镜像
取消镜像后，update速度会慢很多，耐心等待。

错误原文

Your requirements could not be resolved to an installable set of packages.

Problem 1

- The requested package laravelium/sitemap could not be found in any version, there may be a typo in the package name.

Potential causes:

• A typo in the package name
• The package is not available in a stable-enough version according to your minimum-stability setting
  see https://getcomposer.org/doc/04-schema.md#minimum-stability for more details.
• It's a private package and you forgot to add a custom repository to find it

Read https://getcomposer.org/doc/articles/troubleshooting.md for further common problems.