I have installed nginx version: nginx/1.10.3 (Ubuntu)

A website requires to upload files. I use php 7 for handling the upload.

The form:
========

<div class="collapse" id="upload_avatar">
<div class="card card-body">
<form enctype="multipart/form-data" action="" method="post">
<p class="text-left">Upload Avatar:</p>
<input type="hidden" name="MAX_FILE_SIZE" value="300000" />
<input name="image" type="file" /><br>
<button class="form-control mr-sm-2 btn btn-outline-success my-2 my-sm-0" type="submit" name="avatar_upload" aria-controls="collapse_upload_avatar">
Upload
</button>
</form>
</div>
</div>

The php part:
===========

if(isset($_POST["avatar_upload"])){
$verifyimg = getimagesize($_FILES['image']['tmp_name']);

if($verifyimg['mime'] != 'image/png') {
echo "Only PNG images are allowed!";
exit;
}

$uploaddir = '/members/3/';
$uploadfile = $uploaddir . basename($_FILES['image']['name']);

if (move_uploaded_file($_FILES['image']['tmp_name'], $uploadfile)) {
echo "File is valid, and was successfully uploaded.<br>";
} else {
echo "Possible file upload attack!<br>";
}

echo '<pre>';
echo 'info:';
print_r($_FILES);
print "</pre>";
}

It prints out:
=========
Possible file upload attack!
info:Array
(
[image] => Array
(
[name] => Selection_001.png
[type] => image/png
[tmp_name] => /tmp/phpGpp3rB
[error] => 0
[size] => 299338
)
)
There is no /tmp/php* file

There is no file in the /members/3/ directory

The permission is 777 for /members and /members/3


nginx/error.log shows:
=================
PHP message: PHP Warning: move_uploaded_file(/members/3/Selection_001.png): failed to open stream: No such file or directory ... on line 197 PHP message:
PHP Warning: move_uploaded_file(): Unable to move '/tmp/phpGpp3rB' to '/members/3/Selection_001.png'


/etc/nginx/nginx.conf:
=================

user www-data;
worker_processes auto;
pid /run/nginx.pid;

events {
worker_connections 768;
# multi_accept on;
}

http {

##
# Basic Settings
##

sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
# server_tokens off;

# server_names_hash_bucket_size 64;
# server_name_in_redirect off;

include /etc/nginx/mime.types;
default_type application/octet-stream;

##
# SSL Settings
##

ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
ssl_prefer_server_ciphers on;

##
# Logging Settings
##

access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;

##
# Gzip Settings
##

gzip on;
gzip_disable "msie6";

# gzip_vary on;
# gzip_proxied any;
# gzip_comp_level 6;
# gzip_buffers 16 8k;
# gzip_http_version 1.1;
# gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

##
# Virtual Host Configs
##

include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}


The sites-available/example.com
==========================

server {
listen 80;
listen [::]:80;

root /home/ronald/docker-websites/example.com;

# Add index.php to the list if you are using PHP
index index.php index.html index.htm index.nginx-debian.html;

server_name example.com;

location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
try_files $uri $uri/ =404;
}

location ~ \.php$ {
include snippets/fastcgi-php.conf;
fastcgi_pass unix:/run/php/php7.0-fpm.sock;
}

location ~ /\.ht {
deny all;
}


listen 443 ssl; # managed by Certbot
ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/example.com/privkey.pem; # managed by Certbot
include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot


if ($scheme != "https") {
return 301 https://$host$request_uri;
} # managed by Certbot


}

What am I missing?