Warning: mkdir(): Permission denied in /var/www/vendor/slothsoft/core/src/Configuration/DirectoryConfigurationField.php on line 19

Fatal error: Uncaught RuntimeException: Could not create directory: /var/www/cache in /var/www/vendor/slothsoft/core/src/Configuration/DirectoryConfigurationField.php:23
Stack trace:
#0 /var/www/vendor/slothsoft/core/src/ServerEnvironment.php(51): Slothsoft\Core\Configuration\DirectoryConfigurationField->setValue('/var/www/cache')
#1 /var/www/src/bootstrap.php(14): Slothsoft\Core\ServerEnvironment::setCacheDirectory('/var/www/cache')
#2 /var/www/vendor/composer/autoload_real.php(42): require('/var/www/src/bo...')
#3 /var/www/vendor/composer/autoload_real.php(46): {closure}('b2d00faaeb73643...', '/var/www/vendor...')
#4 /var/www/vendor/autoload.php(25): ComposerAutoloaderInit933143e81c02e824fcb13e483bd2c417::getLoader()
#5 /usr/share/farah/index.php(8): require_once('/var/www/vendor...')
#6 {main}
  thrown in /var/www/vendor/slothsoft/core/src/Configuration/DirectoryConfigurationField.php on line 23