在nginx配置文件中删除了index.php就报错

[root@izkbs00av8xzccz conf.d]# systemctl restart nginx
Job for nginx.service failed because the control process exited with error code. See "systemctl status nginx.service" and "journalctl -xe" for details.
[root@izkbs00av8xzccz conf.d]# vim default.conf
###################### Default ################################
server
{
    listen 80 default_server;
    server_name www.mydomain.com mydomain.com;
    index index.html index.htm index.php; #此行我去掉了index.php 和前面的index就出现报错
    root  /data/wwwroot/default;
    error_log /var/log/nginx/default-error.log crit;
    location ~ .*\.php$
    {
        fastcgi_pass  unix:/dev/shm/php-fpm-default.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include fastcgi_params;
        try_files $uri = 404;
    }
    location ~ .*\.(gif|jpg|jpeg|png|bmp|swf|flv|mp3|wma|mp4|ico)$
    {
        expires      30d;
        access_log off;
    }
    location ~ .*\.(js|css)$
    {
        expires      7d;
        access_log off;
    }
    location ~* \.(ftpquota|htaccess|htpasswd|asp|aspx|jsp|asa|mdb)?$ {
        deny all;
    }
################################ SSL #########################################
#listen 443 ssl;
#ssl on;
#ssl_certificate /data/cert/xxx.crt;
#ssl_certificate_key /data/cert/xxx.key
#ssl_session_timeout 5m;
#ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
#ssl_ciphers ECDHE-RSA-AES128-GCM-SHA256:HIGH:!aNULL:!MD5:!RC4:!DHE;
#ssl_prefer_server_ciphers
## 301 重定向 http => https
#if ( != "https") {
#return 301 https://;
#}
############################### extra ########################################
     include /etc/nginx/conf.d/extra/*.conf;
}
[root@izkbs00av8xzccz conf.d]# systemctl restart nginx #正确