Upgrade to Ghost 3.02 - Can't connect to the bootstrap socket (localhost 8000) ECONNREFUSED

Developer help
1

I have recently upgraded a blog from ghost 2.x to 3.02 and since then I am getting issues with connection on the bootstrap socket. The instance starts, with no issues when running ghost doctor, but pages will very frequently give a 502 bad Gateway error (loading only after multiple refreshes), and images will not load, or will only partially load.

URL: https://news.x51squadron.com

ghost log output looks like this after loading a page (also the same output if I try ghost run):

[2019-10-31 13:32:31] INFO Ghost is running in production...
[2019-10-31 13:32:31] INFO Your site is now available on https://news.x51squadron.com/
[2019-10-31 13:32:31] INFO Ctrl+C to shut down
[2019-10-31 13:32:31] WARN Can't connect to the bootstrap socket (localhost 8000) ECONNREFUSED
[2019-10-31 13:32:31] WARN Tries: 0
[2019-10-31 13:32:31] WARN Retrying...
[2019-10-31 13:32:31] WARN Can't connect to the bootstrap socket (localhost 8000) ECONNREFUSED
[2019-10-31 13:32:31] WARN Tries: 1
[2019-10-31 13:32:31] WARN Retrying...
[2019-10-31 13:32:31] WARN Can't connect to the bootstrap socket (localhost 8000) ECONNREFUSED
[2019-10-31 13:32:31] WARN Tries: 2
[2019-10-31 13:32:31] WARN Retrying...
[2019-10-31 13:32:32] WARN Can't connect to the bootstrap socket (localhost 8000) ECONNREFUSED
[2019-10-31 13:32:32] INFO Ghost boot 4.317s
[2019-10-31 13:33:33] INFO "GET /" 301 10ms

My ghost config looks like this:
{
“url”: “https://news.x51squadron.com”,
“server”: {
“port”: 2370,
“host”: “127.0.0.1”
},
“database”: {
“client”: “mysql”,
“connection”: {
“host”: “localhost”,
“user”: “ghost”,
“password”: xxxxxxxxx

...

  "process": "systemd",
  "paths": {
"contentPath": "/var/www/ghost/content"
  },
  "bootstrap-socket": {
"port": 8000,
"host": "localhost"
  }
}

nginx block:
server {
listen 443 ssl http2;
listen [::]:443 ssl http2;

        server_name news.x51squadron.com;
        root /var/www/ghost/system/nginx-root;

        ssl_certificate /etc/letsencrypt/news.x51squadron.com/fullchain.cer;
        ssl_certificate_key /etc/letsencrypt/news.x51squadron.com/news.x51squadron.com.key;
        include /etc/nginx/snippets/ssl-params.conf;

        location / {
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header Host $http_host;
            proxy_pass http://127.0.0.1:2370;

        }

        location ~ /.well-known {
            allow all;
        }

        client_max_body_size 50m;
    }

thanks!