Problem updating from Drupal Core 8.3.7 to 8.4.0 with composer I am having trouble updating from Drupal 8.3.7.

When running composer why-not drupal/core 8.4.0 I get the following results:

drupal/core 8.4.0 requires symfony/class-loader (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/class-loader (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/console (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/console (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/dependency-injection (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/dependency-injection (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/event-dispatcher (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/event-dispatcher (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/http-foundation (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/http-foundation (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/http-kernel (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/http-kernel (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/process (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/process (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/routing (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/routing (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/serializer (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/serializer (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/translation (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/translation (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/validator (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/validator (but v2.8.28 is installed)
drupal/core 8.4.0 requires symfony/yaml (~3.2.8)
andeersg/bouvet-d8-project dev-Stinis does not require symfony/yaml (but v2.8.28 is installed)


Trying to update one of the mentioned packages just results in composer telling me I can't because Drupal 8.3.7 needs a lower version. So I can't update the packages and I can't update Drupal. Am I stuck in a catch22?

Does anybody know what the problem might be? When I run composer update drupal/core --with-dependencies it says that everything is up to date even though it is still at 8.3.7.
I had the same issue and here is what worked for me

Requirement : PHP 7.1
Explanation :1. Doctrire, a dependancy of Drupal core, requires PHP 7.1. Doctrine uses the latest PHP 7.1 syntax to declare the methods' return type eg. function my_function() : void {...}. There is a core bug concerning this issue with status "Needs work". Even if this bug is patched, 8.4 requires PHP 7.
2. webflo breaks the chain of dependencies
3. Drupal 8.4 requires Drush 9.0

If you have PHP 7.1 on your server you can do the following:


edit the composer.json file: "drupal/core": "~8.4" and "drush/drush": "~9.0"
delete composer.lock
delete vendor
update webflo: composer require "webflo/drupal-finder ~1.0.0"
update the database: ../vendor/bin/drush updb -y
update the entities schemas: ../vendor/bin/drush entup -y


Applied on three different production servers (Linux + Apache) and on local environments (macOS + Apach, Ubuntu + Apache). Not tested with Vagrant.

The two entity updates are concerning "paragraph entity type" : (1) The Published field needs to be updated. (2) The Behavior settings field needs to be updated.