504 网关超时错误 - 上游读取响应标头时超时

Question

我将运行 Ubuntu 14.04 的 vagrant 上的 nginx 1.11 和 PHP 7.1 升级到 nginx 1.13.1 和 PHP 7.2。

确认两项服务均已运行。

现在，当我尝试访问任何example.test网站时，什么都没有发生。浏览器只是无限期地等待加载，直到最终出现错误504 Gateway Time-out，并显示在“”中：

2018/01/14 23:51:55 [error] 3058#3058: *1 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.10.1, server: example.test, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.0-fpm.sock", host: "192.168.10.10"

访问example.test不起作用，并且192.168.10.10它映射到我的主机上也不起作用。

我/var/log/nginx/error.log只看到这个：

2018/01/14 23:41:55 [notice] 3052#3052: signal process started

我/var/log/nginx/example.test-access.log只看到这个：

192.168.10.1 - - [14/Jan/2018:23:42:04 +0000] "GET / HTTP/1.1" 499 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36"

我的/etc/nginx/sites-enabled/example.test配置文件包含：

server {
    listen 80;
    listen 443 ssl;
    server_name example.test;
    root "/home/vagrant/Projects/example.test/public";

    index index.html index.htm index.php;

    charset utf-8;

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

    location = /favicon.ico { access_log off; log_not_found off; }
    location = /robots.txt  { access_log off; log_not_found off; }

    access_log /var/log/nginx/example.test-access.log;
    error_log  /var/log/nginx/example.test-error.log error;

    sendfile off;

    client_max_body_size 100m;

    location ~ \.php$ {
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;

        fastcgi_intercept_errors off;
        fastcgi_buffer_size 32k;
        fastcgi_buffers 16 32k;
        fastcgi_connect_timeout 600;
        fastcgi_send_timeout 600;
        fastcgi_read_timeout 600;
    }

    location ~ /\.ht {
        deny all;
    }

    ssl_certificate     /etc/nginx/ssl/example.test.crt;
    ssl_certificate_key /etc/nginx/ssl/example.test.key;
}

什么原因造成这里的挂断？