Nginx "413 Request Entity Too Large": raise the upload limit in the right place

1. Set the limit in nginx

client_max_body_size works in the http, server and location blocks; the most specific one wins. Put it where it makes sense:

• in the server block, for the whole site;
• or only in the location that handles uploads, keeping the small default elsewhere:

location /upload {
    client_max_body_size 200m;
    proxy_pass http://127.0.0.1:3000;
}

0 turns the check off — avoid it on public sites, it lets anyone send endless data. After the change, test and reload; a reload is enough:

sudo nginx -t && sudo systemctl reload nginx

If nothing changes, check that you edited the file nginx really uses and that no more specific block sets a smaller value: sudo nginx -T | grep -n client_max_body_size lists every one. The Nginx Config Generator has a “max upload size” field that sets it for you.

2. The next limit: your application

Once nginx lets the request through, the app may refuse it in its own way.

PHP (PHP-FPM) — two settings in php.ini (on Debian/Ubuntu /etc/php/8.3/fpm/php.ini), and post_max_size must be at least as big as upload_max_filesize:

upload_max_filesize = 50M
post_max_size = 55M

Then sudo systemctl restart php8.3-fpm (or php-fpm on RHEL). A too-small PHP limit doesn’t always show an error: the upload may simply arrive empty.

Node.js / Express — the JSON parser’s default limit is 100 kB, and the error looks almost the same: PayloadTooLargeError: request entity too large, status 413 — but from Express, not nginx. Raise it where the parser is set up: app.use(express.json({ limit: '10mb' })). File uploads with a library like multer have their own limits.fileSize.

Other frameworks have similar settings: Django DATA_UPLOAD_MAX_MEMORY_SIZE, Spring spring.servlet.multipart.max-file-size, ASP.NET MaxRequestBodySize.

3. The layers in front of nginx

• Kubernetes with ingress-nginx — the ingress controller is an nginx too, with its own limit. Set it per Ingress:

metadata:
  annotations:
    nginx.ingress.kubernetes.io/proxy-body-size: 50m

• A CDN or cloud load balancer — many have a fixed maximum request size on their plans (Cloudflare’s Free and Pro plans, for example, stop at 100 MB). For very large files, upload directly to object storage (S3 presigned URLs and similar) instead of through your server.

To find which layer says 413, look at the response: nginx’s page says nginx at the bottom, other layers answer with their own page or JSON. Check the logs in order — from the outermost layer to your app.