Help needed with configuration

[Ian]

Hi,

I have the following configuration. Why are a missing .html file, and 
the requests for favicon.ico (also missing), all  result in a "bad 
gateway" error.? The error log shows that the request is passed to 
uwsgi, which is aborting 502.

I would have expected the last two configurations to be taken resulting 
in a 404.

server {
     listen  80;
     listen [::]:80 ipv6only=on;
     server_name www.mydomain.com mydomain.com, wwp.mydomain.com localhost;
     # localhost so it can be read locally for testing

     access_log /var/log/nginx/gmt.access.log;
     error_log /var/log/nginx/gmt.error.log;
     index index.htm;
     # three way split -> .htm .php and static
     # serve old *.htm, send missing to new
     location ~ \.htm$ {
         root /var/www/mydomain.com/oldhtdocs;
         try_files $uri $uri/ @newflask;
     }
     # for new site, pass .htm to flask
     location @newflask {
         # recieves *.htm where old file is missing
         root /var/www/mydomain.com/htdocs;
         include                     uwsgi_params;
         try_files $uri =404;
         fastcgi_split_path_info ^(.+\.htm)(/.+)$;
         uwsgi_pass                  uwsgicluster;
         uwsgi_param UWSGI_CHDIR     /var/www/mydomain.com/flask;
         uwsgi_param UWSGI_PYHOME /var/www/mydomain.com/flask/venv;
         uwsgi_param UWSGI_MODULE    gmt;
         uwsgi_param UWSGI_CALLABLE  app;
         proxy_redirect              off;
         proxy_set_header            Host $host;
         proxy_set_header            X-Real-IP $remote_addr;
         proxy_set_header            X-Forwarded-For 
$proxy_add_x_forwarded_for;
         proxy_set_header            X-Forwarded-Host $server_name;
     }
     # Pass php files to php via fcgi
     location ~ \.php$ {
         root /var/www/mydomain.com/oldhtdocs;
         try_files $uri @newphp;
         fastcgi_split_path_info ^(.+\.php)(/.+)$;
         # NOTE: Must have "cgi.fix_pathinfo = 0;" in php.ini
         fastcgi_pass unix:/var/run/php5-fpm.sock;
         fastcgi_index index.php;
         include fastcgi_params;
     }
     # pass .php to new root or 404
     location @newphp {
         root /var/www/mydomain.com/htdocs;
         try_files $uri =404;
         fastcgi_split_path_info ^(.+\.php)(/.+)$;
         fastcgi_pass unix:/var/run/php5-fpm.sock;
         fastcgi_index index.php;
         include fastcgi_params;
     }
     # serve old static files with nginx
     location / {
        root /var/www/mydomain.com/oldhtdocs;
        index index.htm;
        try_files $uri $uri/ @newstatic;
     }
     # serve static new files with nginx
     location @newstatic {
         root /var/www/mydomain.com/htdocs;
             # serve if present, else 404
         try_files $uri $uri/ =404;
     }
}

By way of explanation, we are migrating from oldhtdocs to a new site, 
but having to replace pages in groups. This way I hope we can leave all 
the junk behind.

Ubuntu 14:04, with standard versions of all software. Nginx is 1.4.6

Thanks for your ideas,

Ian