Warning: require(/magento/app/bootstrap.php): failed to open stream: No such file or directory in /magento/index.php on line 22

Warning: require(/magento/app/bootstrap.php): failed to open stream: No such file or directory in /magento/index.php on line 22

Fatal error: require(): Failed opening required '/magento/app/bootstrap.php' (include_path='.:/:/usr/local/php71/lib/pear') in /magento/index.php on line 22