Run this command to enable dev mode by turning debug flag to true and turning configuration caching to off. It will also make sure that any existing config cache is cleared.
composer development-enable.dist extension from config/autoload/development.global.php.dist.DotKernel comes with its own DebugBar already installed and configured. It is enabled when you clone the config file config/autoload/debugbar.local.php.dist as config/autoload/debugbar.local.php. You can disable the tool by going into its config file config/autoload/debugbar.local.php and changing
'enabled' => trueto
'enabled' => false