Fatal error: Uncaught Error: Class "Composer\Installers\BaseInstaller" not found in /home/aipnbsfo/public_html/vendor/composer/installers/src/Composer/Installers/MantisBTInstaller.php:6 Stack trace: #0 {main} thrown in /home/aipnbsfo/public_html/vendor/composer/installers/src/Composer/Installers/MantisBTInstaller.php on line 6