[Fixed] nginx - upstream sent too big header

Hi.
I have a Ubuntu 22.04 server, and I run nginx and WordPress. But I have some problems with:

"nginx - upstream sent too big header while reading response header from upstream"

The site gives: 502 Bad Gateway

Code:

2023/05/14 10:23:32 [error] 489662#489662: *1 upstream sent too big header while reading response header from upstream, client: 5.186.54.48, server: futurenode.dk, request: "GET /wp-login.php?redirect_to=https%3A%2F%2Fwww.futurenode.dk%2Fwp-admin%2F&reauth=1 HTTP/2.0", upstream: "fastcgi://unix:/run/php/php8.2-fpm.sock:", host: "www.futurenode.dk"
2023/05/14 10:23:33 [error] 489662#489662: *1 upstream sent too big header while reading response header from upstream, client: 5.186.54.48, server: futurenode.dk, request: "GET /wp-login.php?redirect_to=https%3A%2F%2Fwww.futurenode.dk%2Fwp-admin%2F&reauth=1 HTTP/2.0", upstream: "fastcgi://unix:/run/php/php8.2-fpm.sock:", host: "www.futurenode.dk"
2023/05/14 10:24:12 [error] 489662#489662: *1 upstream sent too big header while reading response header from upstream, client: 5.186.54.48, server: futurenode.dk, request: "GET /wp-login.php?action=logout&_wpnonce=21ed9a713d HTTP/2.0", upstream: "fastcgi://unix:/run/php/php8.2-fpm.sock:", host: "www.futurenode.dk", referrer: "https://www.futurenode.dk/wp-admin/profile.php"
2023/05/14 10:24:31 [error] 489662#489662: *1 upstream sent too big header while reading response header from upstream, client: 5.186.54.48, server: futurenode.dk, request: "GET /wp-login.php?redirect_to=https%3A%2F%2Fwww.futurenode.dk%2Fwp-admin%2F&reauth=1 HTTP/2.0", upstream: "fastcgi://unix:/run/php/php8.2-fpm.sock:", host: "www.futurenode.dk"
2023/05/14 10:27:06 [error] 490164#490164: *1 upstream sent too big header while reading response header from upstream, client: 5.186.54.48, server: futurenode.dk, request: "GET /wp-login.php?redirect_to=https%3A%2F%2Fwww.futurenode.dk%2Fwp-admin%2F&reauth=1 HTTP/2.0", upstream: "fastcgi://unix:/run/php/php8.2-fpm.sock:", host: "www.futurenode.dk"

My vHost look like this:

Code:

server {


    # Declare the domain name of the website
    server_name futurenode.dk www.futurenode.dk;

    # Declare the document root directory
    root  /home/futurenode/www;

    client_max_body_size 500M;

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

    index index.html index.php;


    # Pass PHP files to PHP-FPM listening on /run/php/php8.1-fpm.sock
    location ~ \.php$ {
        try_files $uri =404;

        # Mitigate https://httpoxy.org/ vulnerabilities
        fastcgi_param HTTP_PROXY "";

        fastcgi_pass unix:/run/php/php8.2-fpm.sock;
        fastcgi_index index.php;
        include fastcgi.conf;
    }

    location / {
    
    # Tune Nginx buffers #

    proxy_buffer_size   128k;
    proxy_buffers   4 256k;
    proxy_busy_buffers_size   256k;
    
    # rest of the nginx config below #


    try_files $uri $uri/ /index.php?$args;


    location ~* /uploads/.*\.php$ {
        return 503;
    }

        # Wordfence
        location ~ ^/\.user\.ini {
        deny all;
        }

    
    }

    location ~ (([^/]*)sitemap(.*)|news|author|video(.*))\.x(m|s)l$ {
    ## SEOPress
    rewrite ^.*/sitemaps\.xml$ /index.php?seopress_sitemap=1 last;
    rewrite ^.*/news.xml$ /index.php?seopress_news=$1 last;
    rewrite ^.*/video.xml$ /index.php?seopress_video=$1 last;
    rewrite ^.*/author.xml$ /index.php?seopress_author=$1 last;
    rewrite ^.*/sitemaps_xsl\.xsl$ /index.php?seopress_sitemap_xsl=1 last;
    rewrite ^.*/sitemaps_video_xsl\.xsl$ /index.php?seopress_sitemap_video_xsl=1 last;
    rewrite ^.*/([^/]+?)-sitemap([0-9]+)?.xml$ /index.php?seopress_cpt=$1&seopress_paged=$2 last;

    }

    listen [::]:443 ssl http2; # managed by Certbot
    listen 443 ssl http2; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/futurenode.dk/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/futurenode.dk/privkey.pem; # managed by Certbot
    #include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-SHA384;
    add_header Strict-Transport-Security "max-age=63072000; includeSubDomains; preload";
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
 }

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


    if ($host = futurenode.dk) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    listen 80;
    listen [::]:80;
    server_name futurenode.dk www.futurenode.dk;
    return 404; # managed by Certbot
}

I have followed the info from this guide: https://www.howtoforge.com/nginx-up...r-while-reading-response-header-from-upstream

Hope someone can help me.

 

I used this instead:

Code:

fastcgi_buffers 16 16k;
fastcgi_buffer_size 32k;

 

Thank you for sharing your problem and its solution. Might be useful for me and others that are running Ubuntu 22.04 nginx web server as well.