title: updating symfony 2.6 to 2.7
body: <p>im trying to update symfony 2.6 to 2.7 </p>
  
  <p>i've changed in my composer.json to 2.7 version </p>
  
  <pre><code>"symfony/symfony": "2.7.*"
  </code></pre>
  
  <p>im running </p>
  
  <pre><code>composer update symfony/symfony --with-dependencies
  </code></pre>
  
  <p>and getting this error </p>
  
  <pre><code>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: don't install symfony/symfony v2.7.41
      - Conclusion: don't install symfony/symfony v2.7.40
      ........
      - Conclusion: don't install symfony/symfony v2.7.2
      - Conclusion: don't install symfony/symfony v2.7.1
      - don't install symfony/asset v3.4.4|don't install symfony/symfony v2.7.0
      - don't install symfony/symfony v2.7.0|remove symfony/asset v3.4.4
      - don't install symfony/symfony v2.7.0|don't install symfony/asset v3.4.4
      - Installation request for symfony/symfony 2.7.* -&gt; satisfiable by symfony/symfony[v2.7.0, v2.7.1, v2.7.10, v2.7.11, v2.7.12, v2.7.13, v2.7.14, v2.7.15, v2.7.16, v2.7.17, v2.7.18, v2.7.19, v2.7.2
  , v2.7.20, v2.7.21, v2.7.22, v2.7.23, v2.7.24, v2.7.25, v2.7.26, v2.7.27, v2.7.28, v2.7.29, v2.7.3, v2.7.30, v2.7.31, v2.7.32, v2.7.33, v2.7.34, v2.7.35, v2.7.36, v2.7.37, v2.7.38, v2.7.39, v2.7.4, v
  2.7.40, v2.7.41, v2.7.5, v2.7.6, v2.7.7, v2.7.8, v2.7.9].
      - Installation request for symfony/asset (locked at v3.4.4) -&gt; satisfiable by symfony/asset[v3.4.4].
  </code></pre>
  
  <p>i dont understand what it wants from me </p>
  
  <p>here is my composer.json</p>
  
  <pre><code>{
      "name": "symfony/framework-standard-edition",
      "license": "MIT",
      "type": "project",
      "description": "The \"Symfony Standard Edition\" distribution",
      "autoload": {
          "psr-0": { "": "src/", "SymfonyStandard": "app/" }
      },
      "require": {
  
  
   "php": "&gt;=5.3.9",
      "doctrine/doctrine-bundle": "~1.2",
      "doctrine/orm": "~2.2,&gt;=2.2.3",
      "incenteev/composer-parameter-handler": "~2.0",
      "sensio/distribution-bundle": "~3.0",
      "sensio/framework-extra-bundle": "~3.0",
      "symfony/assetic-bundle": "~2.3",
      "symfony/monolog-bundle": "~2.4",
      "symfony/swiftmailer-bundle": "~2.3",
      "symfony/symfony": "2.7.*",
      "twig/extensions": "~1.0",
      "gedmo/doctrine-extensions": "^2.3.1",
      "stof/doctrine-extensions-bundle": "dev-master",
      "symfony/dom-crawler": "~2.6",
      "friendsofsymfony/user-bundle": "~2.0@dev",
      "ircmaxell/password-compat": "^1.0",
      "helios-ag/fm-elfinder-bundle": "~5",
      "egeloen/ckeditor-bundle": "^3.0",
      "vich/uploader-bundle": "^1.4",
      "google/apiclient": "~2.0",
      "masih/youtubedownloader": "^2.8"
      },
      "require-dev": {
          "sensio/generator-bundle": "~2.3"
      },
      "scripts": {
          "post-root-package-install": [
              "SymfonyStandard\\Composer::hookRootPackageInstall"
          ],
          "post-install-cmd": [
              "Incenteev\\ParameterHandler\\ScriptHandler::buildParameters",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::removeSymfonyStandardFiles"
          ],
          "post-update-cmd": [
              "Incenteev\\ParameterHandler\\ScriptHandler::buildParameters",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
              "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::removeSymfonyStandardFiles"
          ]
      },
      "config": {
          "bin-dir": "bin",
          "component-dir": "web/assets"
      },
      "extra": {
          "symfony-app-dir": "app",
          "symfony-web-dir": "web",
          "incenteev-parameters": {
              "file": "app/config/parameters.yml"
          },
          "branch-alias": {
              "dev-master": "2.7-dev"
          }
      }
  }
  </code></pre>
  
  <p>i've updated symfony/assets separately but it did not help
  also tried updating  sensio/framework-extra-bundle and vich/uploader-bundle
  which are referencing the symfoy/asset bundle 
  this also did not help</p>