title: Composer require. "Your requirements could not be resolved to an installable set of packages"
body: <p>I have an error when I want to run the <code>composer require</code> on my project. errors issued like this:</p>
  
  <pre><code># composer require spatie/laravel-link-checker
  Using version ^4.1 for spatie/laravel-link-checker
  ./composer.json has been updated
  Loading composer repositories with package information
  Updating dependencies (including require-dev)
  Your requirements could not be resolved to an installable set of packages.
  
    Problem 1
      - Conclusion: remove laravel/framework v5.8.18
      - Conclusion: don't install laravel/framework v5.8.18
      - spatie/laravel-link-checker 4.1.0 requires illuminate/support ~5.6.0 -&gt; satisfiable by illuminate/support[5.6.x-dev, v5.6.0, v5.6.1, v5.6.10, v5.6.11, v5.6.12, v5.6.13, v5.6.14, v5.6.15, v5.6.16, v5.6.17, v5.6.19, v5.6.2, v5.6.20, v5.6.21, v5.6.22, v5.6.23, v5.6.24, v5.6.25, v5.6.26, v5.6.27, v5.6.28, v5.6.29, v5.6.3, v5.6.30, v5.6.31, v5.6.32, v5.6.33, v5.6.34, v5.6.35, v5.6.36, v5.6.37, v5.6.38, v5.6.39, v5.6.4, v5.6.5, v5.6.6, v5.6.7, v5.6.8, v5.6.9], laravel/framework[5.6.x-dev].
      - spatie/laravel-link-checker 4.1.1 requires laravel/framework ~5.6.0|~5.7.0 -&gt; satisfiable by laravel/framework[5.6.x-dev, 5.7.x-dev].
      - don't install illuminate/support 5.6.x-dev|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.0|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.1|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.10|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.11|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.12|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.13|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.14|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.15|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.16|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.17|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.19|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.2|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.20|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.21|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.22|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.23|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.24|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.25|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.26|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.27|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.28|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.29|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.3|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.30|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.31|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.32|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.33|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.34|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.35|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.36|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.37|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.38|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.39|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.4|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.5|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.6|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.7|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.8|don't install laravel/framework v5.8.18
      - don't install illuminate/support v5.6.9|don't install laravel/framework v5.8.18
      - Can only install one of: laravel/framework[5.6.x-dev, v5.8.18].
      - Can only install one of: laravel/framework[5.7.x-dev, v5.8.18].
      - Installation request for laravel/framework (locked at v5.8.18, required as 5.8.*) -&gt; satisfiable by laravel/framework[v5.8.18].
      - Installation request for spatie/laravel-link-checker ^4.1 -&gt; satisfiable by spatie/laravel-link-checker[4.1.0, 4.1.1].
  
  
  Installation failed, reverting ./composer.json to its original content.
  </code></pre>
  
  <p>I'm using Laravel 5.8.</p>
  
  <p>This is my Composer.json</p>
  
  <pre><code>{
      "name": "laravel/laravel",
      "type": "project",
      "description": "The Laravel Framework.",
      "keywords": [
          "framework",
          "laravel"
      ],
      "license": "MIT",
      "require": {
          "php": "^7.1.3",
          "appzcoder/laravel-admin": "^3.1",
          "barryvdh/laravel-debugbar": "^3.2",
          "chriskonnertz/open-graph": "^1.0",
          "cviebrock/eloquent-sluggable": "4.8",
          "davejamesmiller/laravel-breadcrumbs": "5.x",
          "doctrine/dbal": "v2.4.2",
          "fideloper/proxy": "^4.0",
          "gpressutto5/laravel-slack": "^1.1",
          "guzzlehttp/guzzle": "^6.3",
          "intervention/image": "^2.4",
          "laravel/framework": "5.8.*",
          "laravel/slack-notification-channel": "^2.0",
          "laravel/tinker": "^1.0",
          "layershifter/tld-extract": "^2.0",
          "malhal/laravel-geographical": "^1.0",
          "yajra/laravel-datatables-oracle": "^9.0"
      },
      "require-dev": {
          "beyondcode/laravel-dump-server": "^1.0",
          "filp/whoops": "^2.0",
          "fzaninotto/faker": "^1.4",
          "laravel/telescope": "^2.0",
          "mockery/mockery": "^1.0",
          "nunomaduro/collision": "^2.0",
          "phpunit/phpunit": "^7.5"
      },
      "config": {
          "optimize-autoloader": true,
          "preferred-install": "dist",
          "sort-packages": true
      },
      "extra": {
          "laravel": {
              "dont-discover": []
          }
      },
      "autoload": {
  
          "classmap": [
              "database/seeds",
              "database/factories"
          ]
      },
      "autoload-dev": {
          "psr-4": {
              "Tests\\": "tests/"
          }
      },
      "minimum-stability": "dev",
      "prefer-stable": true,
      "scripts": {
          "post-autoload-dump": [
              "Illuminate\\Foundation\\ComposerScripts::postAutoloadDump",
              "@php artisan package:discover --ansi"
          ],
          "post-root-package-install": [
              "@php -r \"file_exists('.env') || copy('.env.example', '.env');\""
          ],
          "post-create-project-cmd": [
              "@php artisan key:generate --ansi"
          ]
      }
  }
  </code></pre>
  
  <p>anyone who can help me?
  Thanks</p>