Creating a New Project Based on an Unstable Symfony Version¶

Suppose that the Symfony 4.0 version hasn't been released yet and you want to create a new project to test its features. First, install the Composer package manager. Then, open a command console, enter your project's directory and execute the following command:

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# Download the latest beta version
$ composer create-project symfony/skeleton my_project "4.0.*" -s beta

# Download the absolute latest commit
$ composer create-project symfony/skeleton my_project "4.0.*" -s dev

Once the command finishes its execution, you'll have a new Symfony project created in the my_project/ directory.

Upgrading your Project to an Unstable Symfony Version¶

Suppose again that Symfony 4.0 hasn't been released yet and you want to upgrade an existing application to test that your project works with it.

First, open the composer.json file located in the root directory of your project. Then, edit the value of all of the symfony/* libraries to the new version and change your minimum-stability to beta:

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{
    "require": {
+         "symfony/framework-bundle": "^4.0",
+         "symfony/finder": "^4.0",
        "...": "..."
    },
+     "minimum-stability": "beta"
}

You can also use set minimum-stability to dev, or omit this line entirely, and opt into your stability on each package by using constraints like 4.0.*@beta.

Finally, from a terminal, update your project's dependencies:

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$ composer update

After upgrading the Symfony version, read the Symfony Upgrading Guide to learn how you should proceed to update your application's code in case the new Symfony version has deprecated some of its features.

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$ cd projects/my_project/
$ git checkout -b testing_new_symfony
# ... update composer.json configuration
$ composer update symfony/symfony

# ... after testing the new Symfony version
$ git checkout master
$ git branch -D testing_new_symfony