Nginx is not picking error_page

Hi Team,

I may need your help on this matter.I am trying to implement a redirection based on 405 error page.But Nginx has not executed my redirection.
Please help me to fix this.I have stuck on this matter from last 2 days.

location / {
resolver 10.79.157.2 valid=30s;
set $upstream_core "ssoapp.devsso.veri.internal:9443";
proxy_pass https://$upstream_core;
error_page 502 /DEV.502.nginx.html;
error_page 405 /DEV.502.nginx.html;
proxy_read_timeout 1200;
proxy_send_timeout 1200;
proxy_connect_timeout 1200;
proxy_ignore_client_abort on;
proxy_http_version 1.1;
proxy_set_header Host $host;
}


location = /DEV.502.nginx.html {
root /opt/applications/nginx/nginx-verison-1.8.0/html/;
}


location = @app {
return 301 /;
}