Fatal error が出る
$ bin/composer update
Fatal error: Uncaught ArgumentCountError: array_merge() does not accept unknown named parameters in phar:///var/www/html/bin/composer/src/Composer/DependencyResolver/DefaultPolicy.php:84
#0 [internal function]: array_merge(slim/slim: Array)
#1 phar:///var/www/html/bin/composer/src/Composer/DependencyResolver/DefaultPolicy.php(84): call_user_func_array('array_merge', Array)
#2 phar:///var/www/html/bin/composer/src/Composer/DependencyResolver/Solver.php(384): Composer\DependencyResolver\DefaultPolicy->selectPreferredPackages(Object(Composer\DependencyResolver\Pool), Array, Array, 'slim/slim')
#3 phar:///var/www/html/bin/composer/src/Composer/DependencyResolver/Solver.php(736): Composer\DependencyResolver\Solver->selectAndInstall(1, Array, Array, Object(Composer\DependencyResolver\GenericRule))
#4 phar:///var/www/html/bin/composer/src/Composer/DependencyResolver/Solver.php(228): Composer\DependencyResolver\Solver->runSat(Array)
#5 phar:///var/www/html/bin/composer/src/Composer/Installer.php(475): Composer\DependencyResolver\Solver->solve(Object(Composer\DependencyResolver\Request), false)
#6 phar:///var/www/html/bin/composer/src/Composer/Installer.php(229): Composer\Installer->doInstall(Object(Composer\Repository\InstalledFilesystemRepository), Object(Composer\Repository\CompositeRepository), Object(Composer\Repository\PlatformRepository), Array)
#7 phar:///var/www/html/bin/composer/src/Composer/Command/UpdateCommand.php(162): Composer\Installer->run()
#8 phar:///var/www/html/bin/composer/vendor/symfony/console/Command/Command.php(245): Composer\Command\UpdateCommand->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#9 phar:///var/www/html/bin/composer/vendor/symfony/console/Application.php(835): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#10 phar:///var/www/html/bin/composer/vendor/symfony/console/Application.php(185): Symfony\Component\Console\Application->doRunCommand(Object(Composer\Command\UpdateCommand), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#11 phar:///var/www/html/bin/composer/src/Composer/Console/Application.php(258): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#12 phar:///var/www/html/bin/composer/vendor/symfony/console/Application.php(117): Composer\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#13 phar:///var/www/html/bin/composer/src/Composer/Console/Application.php(104): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#14 phar:///var/www/html/bin/composer/bin/composer(56): Composer\Console\Application->run()
#15 /var/www/html/bin/composer(24): require('phar:///var/www...')
#16 {main}
thrown in phar:///var/www/html/bin/composer/src/Composer/DependencyResolver/DefaultPolicy.php on line 84
composer をアップデートすると解決する場合がある
$ bin/composer self-update