How to fix 502 Bad Gateway error ( upstream sent too big header while reading response header from upstream ) after clean installation of magento 2.4.x in nginx + apache config or nging + php-fpm?
Just increase your proxy buffer in nginx config using:
apache ( php7.4 ) + nginx ( usually in location @fallback { section ) :
proxy_buffer_size 16k;
proxy_busy_buffers_size 16k;nginx + php-fpm:
fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;