Manual:DefaultSettings.php

DefaultSettings.php is a deprecated stub that in prior versions contained configuration settings. Currently default settings are stored in MainConfigSchema.php .

DefaultSettings.php should never be edited, since any changes made to it will be lost at every upgrade of MediaWiki. Rather, changes should be made to LocalSettings.php .

As of MediaWiki 1.38, including DefaultSettings.php in your LocalSettings.php will result in the error described at T311966:

PHP Fatal error:  Uncaught FatalError: $wgBaseDirectory must not be modified in settings files! Use the MW_INSTALL_PATH environment variable to override the installation root directory. in /var/www/html/w/includes/Setup.php:237
Stack trace:
#0 /var/www/html/w/maintenance/doMaintenance.php(96): require_once()
#1 /var/www/html/w/maintenance/update.php(264): require_once('/var/www/html/w...')
#2 {main}
  thrown in /var/www/html/w/includes/Setup.php on line 237

Fatal error: Uncaught FatalError: $wgBaseDirectory must not be modified in settings files! Use the MW_INSTALL_PATH environment variable to override the installation root directory. in /var/www/html/w/includes/Setup.php:237
Stack trace:
#0 /var/www/html/w/maintenance/doMaintenance.php(96): require_once()
#1 /var/www/html/w/maintenance/update.php(264): require_once('/var/www/html/w...')
#2 {main}
  thrown in /var/www/html/w/includes/Setup.php on line 237