Unrecognized option "resource" under "fos_user"
Dlondero's suggestion fixed the issue, the fos_user configuration should be set in config/routes.yaml.
From documentation, routes are never automatically added in configuration.
If I am not wrong, config/packages/routing.yaml file is not for routes, it is the config file for routing bundle, you can not put your routing configs to there. Instead, you should put them under config/routes folder, as bundle_name.yml.
Like this, eg. config/routes/imagine.yml:
_liip_imagine: resource: "@LiipImagineBundle/Resources/config/routing.yaml"
move the :
fos_user: resource: "@FOSUserBundle/Resources/config/routing/all.xml" into config/routes.yaml insted of confing/packages/routing.yml