I installed Nextcloud 21 with NGINX, postgresql 12 and PHP_FPM. All services were installed and running and configured. But, when try to access the nextcloud site to finish web service and run, its shows me:
404 Not Found - nginx/1.16.1

check the error.log:
tail -f /var/log/nginx/error.log

2021/06/12 15:49:35 [error] 1722#1722: 2 open() “/usr//html/index.php” failed (2: No such file or directory), client: *IP**, server: myservernextcloud, request: “GET /index.php HTTP/1.1”, host: “myservernextcloud”

my /etc/nginx/vhosts/nextclou.conf

upstream php-handler {
    server 127.0.0.1:9000;
    #server unix:/var/run/php/php7.4-fpm.sock;
}

server {
    server_name my_server;

    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/my_server/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/my_server /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

}

server {
    if ($host = my_server) {
        return 301 https://$host$request_uri;
    } # managed by Certbot

    listen 80;
    listen [::]:80;
    server_name my_server;
    return 404; # managed by Certbot


   # ssl_protocols TLSv1.2 TLSv1.3;
   # ssl_ciphers HIGH:!MEDIUM:!LOW:!aNULL:!NULL:!SHA;
   # ssl_prefer_server_ciphers on;
   # ssl_session_cache shared:SSL:10m;

    # HSTS settings
    # WARNING: Only add the preload option once you read about
    # the consequences in https://hstspreload.org/. This option
    # will add the domain to a hardcoded list that is shipped
    # in all major browsers and getting removed from this list
    # could take several months.
   add_header Strict-Transport-Security  "max-age=31536000; includeSubDomains"   always;

    # set max upload size
    client_max_body_size 512M;
    fastcgi_buffers 64 4K;

    # Enable gzip but do not remove ETag headers
    gzip on;
    gzip_vary on;
    gzip_comp_level 4;
    gzip_min_length 256;
    gzip_proxied expired no-cache no-store private no_last_modified no_etag auth;
    gzip_types application/atom+xml application/javascript application/json application/ld+json application/manifest+json application/rss+xml application/vnd.geo+json application/vnd.ms-fontobject application/x-font-ttf application/x-web-app-manifest+json application/xhtml+xml application/xml font/opentype image/bmp image/svg+xml image/x-icon text/cache-manifest text/css text/plain text/vcard text/vnd.rim.location.xloc text/vtt text/x-component text/x-cross-domain-policy;

    # Pagespeed is not supported by Nextcloud, so if your server is built
    # with the `ngx_pagespeed` module, uncomment this line to disable it.
    #pagespeed off;

    # HTTP response headers borrowed from Nextcloud `.htaccess`
    add_header Referrer-Policy                      "no-referrer"           always;
    add_header X-Content-Type-Options               "nosniff"               always;
    add_header X-Download-Options                   "noopen"                always;
    add_header X-Frame-Options                      "SAMEORIGIN"            always;
    add_header X-Permitted-Cross-Domain-Policies    "none"                  always;
    add_header X-Robots-Tag                         "none"                  always;
    add_header X-XSS-Protection                     "1; mode=block"         always;

    # Opt out of Google Chrome tracking everything you do.
    # Note: if you’re reading this, stop using Google Chrome.
    # It is ridiculous for web servers to essentially have to ask
    # “please do not violate the privacy of the people who are viewing
    # this site” with every request.
    # For more info, see: https://plausible.io/blog/google-floc
    add_header Permissions-Policy                   "interest-cohort=()"    always;

    # Remove X-Powered-By, which is an information leak
    fastcgi_hide_header X-Powered-By;

    # Path to the root of your installation
    root /srv/www/htdocs/nextcloud;


    # Specify how to handle directories -- specifying `/index.php$request_uri`
    # here as the fallback means that Nginx always exhibits the desired behaviour
    # when a client requests a path that corresponds to a directory that exists
    # on the server. In particular, if that directory contains an index.php file,
    # that file is correctly served; if it doesn't, then the request is passed to
    # the front-end controller. This consistent behaviour means that we don't need
    # to specify custom rules for certain paths (e.g. images and other assets,
    # `/updater`, `/ocm-provider`, `/ocs-provider`), and thus
    # `try_files $uri $uri/ /index.php$request_uri`
    # always provides the desired behaviour.
    index index.php index.html /index.php$request_uri;


    # Rule borrowed from `.htaccess` to handle Microsoft DAV clients
    location = / {
        if ( $http_user_agent ~ ^DavClnt ) {
            return 302 /remote.php/webdav/$is_args$args;
        }
    }

    location = /robots.txt {
        allow all;
        log_not_found off;
        access_log off;
    }

    # Make a regex exception for `/.well-known` so that clients can still
    # access it despite the existence of the regex rule
    # `location ~ /(\.|autotest|...)` which would otherwise handle requests
    # for `/.well-known`.
    location ^~ /.well-known {
        # The following 6 rules are borrowed from `.htaccess`

        location = /.well-known/carddav     { return 301 /remote.php/dav/; }
        location = /.well-known/caldav      { return 301 /remote.php/dav/; }
        # Anything else is dynamically handled by Nextcloud
        location ^~ /.well-known            { return 301 /index.php$uri; }

        try_files $uri $uri/ =404;
    }

    # Rules borrowed from `.htaccess` to hide certain paths from clients
    location ~ ^/(?:build|tests|config|lib|3rdparty|templates|data)(?:$|/)  { return 404; }
    location ~ ^/(?:\.|autotest|occ|issue|indie|db_|console)              { return 404; }

    # Ensure this block, which passes PHP files to the PHP process, is above the blocks
    # which handle static assets (as seen below). If this block is not declared first,
    # then Nginx will encounter an infinite rewriting loop when it prepends `/index.php`
    # to the URI, resulting in a HTTP 500 error response.


     location ~ \.php$ {
                # 404
                try_files                     $fastcgi_script_name =404;

                # default fastcgi_params
                include                       /etc/nginx/fastcgi_params;

                # fastcgi settings
                fastcgi_pass                  127.0.0.1:9000;
                fastcgi_index                 index.php;
                fastcgi_buffers               8 16k;
                fastcgi_buffer_size           32k;

                # fastcgi params
                fastcgi_param DOCUMENT_ROOT   $realpath_root;
                fastcgi_param SCRIPT_FILENAME $realpath_root$fastcgi_script_name;
        }     


    location ~ \.(?:css|js|svg|gif)$ {
        try_files $uri /index.php$request_uri;
        expires 6M;         # Cache-Control policy borrowed from `.htaccess`
        access_log off;     # Optional: Don't log access to assets
    }

    location ~ \.woff2?$ {
        try_files $uri /index.php$request_uri;
        expires 7d;         # Cache-Control policy borrowed from `.htaccess`
        access_log off;     # Optional: Don't log access to assets
    }

    location /nextcloud {
        try_files $uri $uri/ /nextcloud/index.php$request_uri;
    } 

   # location / {
   #    # try_files $uri $uri/ /index.php$request_uri;
   #     try_files $uri $uri/ /index.php?q=$uri&$args;

   # }
}

No errors on postgresql
No errors on php-fpm
no errors on nginx

How can I fix this?
Please, somebody can help me?

Thank you!