After 2 years, I had to make some modifications to a very simple project I created with Symfony 4. At the time, Flex was introduced and I decided to use it on the project, everything went well until today. The problem with Flex now is that the old infrastructure of Flex shut down in May of 2022. So as of now, if you try to install the dependencies of a project that refereces an old version of Symfony Flex, the project will simply throw an error like the following one: error while downloading https://flex.symfony.com/versions.json: Could not resolve host: flex.symfony.com. The following exception probably indicates you have misconfigured DNS resolver(s).
This happened after installing the dependencies as usual in my project using:
The solution for this problem is quite simple fortunately, even Fabien Potencier wrote a short article about how to upgrade the projects to the latest version of flex in this article. To solve this problem, first verify if the problem is cause because of the transition of Flex to a public Github repository running the following command after installing the dependencies:
composer show symfony/flex
If some of your projects uses flex, which is probably the case, it's very likely that the version of Flex is less than v1.17.1. If that's the case you can fix this issue by simply upgrading flex using the following command:
composer update symfony/flex --no-plugins --no-scripts
This should simply update some dependencies and you should be good to go. If you run
composer show symfony/flex again, you will get an output similar to:
name : symfony/flex descrip. : Composer plugin for Symfony keywords : versions : * v1.19.3 type : composer-plugin license : MIT License (MIT) (OSI approved) https://spdx.org/licenses/MIT.html#licenseText homepage : source : [git] https://github.com/symfony/flex.git ab0453b16029e131c112df1a76e59eb2a47e1f67 dist : [zip] https://api.github.com/repos/symfony/flex/zipball/ab0453b16029e131c112df1a76e59eb2a47e1f67 ab0453b16029e131c112df1a76e59eb2a47e1f67 path : names : symfony/flex support issues : https://github.com/symfony/flex/issues source : https://github.com/symfony/flex/tree/v1.19.3 autoload psr-4 Symfony\Flex\ => src requires composer-plugin-api ^1.0|^2.0 php >=7.1 requires (dev) composer/composer ^1.0.2|^2.0 symfony/dotenv ^4.4|^5.0|^6.0 symfony/filesystem ^4.4|^5.0|^6.0 symfony/phpunit-bridge ^4.4.12|^5.0|^6.0 symfony/process ^4.4|^5.0|^6.0
Happy coding ❤️!