报错信息

No composer.lock file present. Updating dependencies to latest instead of installing from lock file. See https://getcomposer.org/install for more information.
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Root composer.json requires fideloper/proxy, it could not be found in any version, there may be a typo in the package name.
  Problem 2
    - Root composer.json requires laravel/framework, it could not be found in any version, there may be a typo in the package name.
  Problem 3
    - Root composer.json requires laravel/tinker, it could not be found in any version, there may be a typo in the package name.
  Problem 4
    - Root composer.json requires beyondcode/laravel-dump-server, it could not be found in any version, there may be a typo in the package name.
  Problem 5
    - Root composer.json requires filp/whoops, it could not be found in any version, there may be a typo in the package name.
  Problem 6
    - Root composer.json requires fzaninotto/faker, it could not be found in any version, there may be a typo in the package name.
  Problem 7
    - Root composer.json requires mockery/mockery, it could not be found in any version, there may be a typo in the package name.
  Problem 8
    - Root composer.json requires nunomaduro/collision, it could not be found in any version, there may be a typo in the package name.
  Problem 9
    - Root composer.json requires phpunit/phpunit, it 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.

方法一

composer install --ignore-platform-reqs 
//或者 
composer update --ignore-platform-reqs 

方法二

//切换源
阿里镜像：composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/
Laravel镜像： composer config -g repo.packagist composer https://packagist.laravel-china.org

中国全量镜像：composer config -g repo.packagist composer https://packagist.phpcomposer.com

//查询是否更换成功
composer config -g -l

//再执行
composer install --ignore-platform-reqs 
//或者 
composer update --ignore-platform-reqs 

报错信息

In PluginManager.php line 738:

  kylekatarnls/update-helper contains a Composer plugin which is blocked by your allow-plugins config. You may add it
   to the list if you consider it safe.
  You can run "composer config --no-plugins allow-plugins.kylekatarnls/update-helper [true|false]" to enable it (true
  ) or disable it explicitly and suppress this exception (false)
  See https://getcomposer.org/allow-plugins

解决

composer install --ignore-platform-reqs--no-plugins