Composer doesn't upgrade Symfony from 3.2 to 3.3 - symfony

Question

I'm trying to upgrade my project to latest Symfony.
The 3.1 to 3.2 was flawless.
Now it's been a hour I'm trying to upgrade to 3.3 and I still do'nt have a clue why it doesn't happen.
The strangest part is I don't have any error message when running the composer update command, but the symfony version doesn't change. I checked on the debug bar and with the bin/console --version command, still 3.2.10.
bin/console --version
Symfony 3.2.10 (kernel: app, env: dev, debug: true)
My composer.json is, I suppose, correctly specified :
"require" : {
"php" : ">=7.0",
"symfony/symfony" : "3.3.*",
"doctrine/orm" : "^2.5",
"doctrine/doctrine-bundle" : "^1.6",
"doctrine/doctrine-cache-bundle" : "^1.2",
"symfony/swiftmailer-bundle" : "^2.3",
"symfony/monolog-bundle" : "^2.8",
"symfony/polyfill-apcu" : "^1.0",
"sensio/distribution-bundle" : "^5.0",
"sensio/framework-extra-bundle" : "^3.0.2",
"incenteev/composer-parameter-handler" : "^2.0",
"symfony/assetic-bundle" : "^2",
"friendsofsymfony/user-bundle" : "~2.0",
"knplabs/knp-menu-bundle" : "^2.0",
"egeloen/ckeditor-bundle" : "^4.0",
"twig/twig" : "#stable",
"twig/extensions" : "^1.4",
"stof/doctrine-extensions-bundle" : "^1.2",
"friendsofsymfony/jsrouting-bundle" : "^1.6",
"yavin/symfony-form-tree" : "~1.0",
"cnerta/breadcrumb-bundle" : "2.1.*",
"symfony/security-acl" : "^v3",
"petrepatrasc/google-map-bundle" : "^2.3",
"debril/rss-atom-bundle" : "^3.0",
"beberlei/DoctrineExtensions" : "^1.0",
"symfony/http-kernel" : "~3.0",
"tilleuls/ovh-bundle" : "1.0.*",
"st/flagiconcss-bundle" : "~1.0",
"th3mouk/yahoo-weather-api" : "^1.0",
"jms/serializer-bundle" : "^1.2"
},
Here is the console output :
composer update
Loading composer repositories with package information
Updating dependencies (including require-dev)
Nothing to install or update
Generating autoload files
> Incenteev\ParameterHandler\ScriptHandler::buildParameters
Updating the "app/config/parameters.yml" file
> Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::buildBootstrap
> Sensio\Bundle\DistributionBundle\Composer\ScriptHandler::clearCache
// Clearing the cache for the dev environment with debug
// And the rest is usual assetic and cache clear stuff
I also tried to upgrade just symfony/symfony, no difference.
Does anyone have a clue ?
Thank you for your time and your help.

Answer 1

The problem is probably that one of your dependencies requires the lower version.
You can use:
composer why symfony/symfony 3.2.*
to find out which dependency it is. Then you probably have to update that dependency first.
To make sure everything works you should do this one by one using:
composer require dependency/dep ?
Where ? is the new version constraint. Then run your tests and then do the same with symfony:
composer update symfony/symfony
OP's edit :
The problem was due to Eclipse not writing the composer.json file to disk anymore, don't ask me why.
However, I mark this answer as the solution because the composer why command is what pushed me in the right direction.