I recently manually upgraded to Drupal 8.4, from 8.3 because I couldn't get drush to work. I'm now trying to install drush locally as this seems to be the recommended way from the drush documentation. (I removed the global install of it I had), but I get the following errors (below).
[www public_html]$ composer require drush/drush
Using version ^8.1 for drush/drush
./composer.json has been updated
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
- drush/drush 8.1.0 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.1 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.2 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.3 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.4 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.5 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.6 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.7 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.8 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- drush/drush 8.1.9 conflicts with drupal/drupal[No version set (parsed as 1.0.0)].
- Conclusion: don't install drush/drush 8.1.14
- Conclusion: don't install drush/drush 8.1.13
- Conclusion: don't install drush/drush 8.1.12
- Conclusion: don't install drush/drush 8.1.11
- Conclusion: don't install drush/drush 8.1.10
- Conclusion: don't install drush/drush 8.x-dev
- Installation request for drupal/drupal No version set (parsed as 1.0.0) -> satisfiable by drupal/drupal[No version set (parsed as 1.0.0)].
- Conclusion: remove symfony/console v3.2.8
- Installation request for symfony/dependency-injection (locked at v3.2.8, required as ~3.2.8) -> satisfiable by symfony/dependency-injection[v3.2.8].
- Installation request for drush/drush ^8.1 -> satisfiable by drush/drush[8.1.0, 8.1.1, 8.1.10, 8.1.11, 8.1.12, 8.1.13, 8.1.14, 8.1.2, 8.1.3, 8.1.4, 8.1.5, 8.1.6, 8.1.7, 8.1.8, 8.1.9, 8.8.x-dev, 8.x-dev].
- Conclusion: don't install symfony/console v3.2.8
- drush/drush 8.8.x-dev requires symfony/console ~2.7 -> satisfiable by symfony/console[2.7.x-dev, 2.8.x-dev].
- Can only install one of: symfony/console[2.7.x-dev, v3.2.8].
- Can only install one of: symfony/console[2.8.x-dev, v3.2.8].
- Installation request for symfony/console (locked at v3.2.8, required as ~3.2.8) -> satisfiable by symfony/console[v3.2.8].
Installation failed, reverting ./composer.json to its original content.
composer require drush/drush:9.*