Laravel project showing 500 error on free 000webhost

This page isn’t working abc.000webhostapp.com is currently unable to handle this request. HTTP ERROR 500

Laravel project uploaded followed by all instructions, still it is giving 500 error.

Warning: require(/storage/ssd5/071/16878071/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php): failed to open stream: No such file or directory in /storage/ssd5/071/16878071/vendor/composer/autoload_real.php on line 71

Warning: require(/storage/ssd5/071/16878071/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php): failed to open stream: No such file or directory in /storage/ssd5/071/16878071/vendor/composer/autoload_real.php on line 71

Fatal error: require(): Failed opening required '/storage/ssd5/071/16878071/vendor/composer/../symfony/polyfill-mbstring/bootstrap.php' (include_path='.:/usr/share/pear:/usr/share/php') in /storage/ssd5/071/16878071/vendor/composer/autoload_real.php on line 71

via Chebli Mohamed