Unexpected behaviour when renaming the query field - field gone

[krzotr]

Issue Details

Hi,

I want to normalize ID query field to be lowercase - id. I use the syntax uri query ID>id.

The thing is, when I go to https://test.dev/?page=test&ID=5&test=100 (ID is uppercase), everything is fine. In the logs of the upstream server, see GET /?id=5&page=test&test=100

When I go https://test.dev/?page=test&id=5&test=100 (id is lowercase), the upstream server does not have the id parameter at all, GET /?page=test&test=100. Caddy removed id parameter!

This is unexpected behavior. Field id (lowercase) must not be touched.

---

How to reproduce:

docker-compose.yml

services:
  caddy:
    image: caddy:2.11.2-alpine
    ports:
      - "8443:443"
    volumes:
      - ./Caddyfile:/etc/caddy/Caddyfile

  node1:
    image: nginx:1.28.3-alpine3.23-perl

Caddyfile

https://test.dev {
  tls internal

  uri query ID>id

  reverse_proxy http://node1:80
}

As expected:

# curl -k -v --connect-to test.dev:443:127.0.0.1:8443 'https://test.dev/?page=test&ID=5&test=100'
node1-1  | 172.21.0.2 - - [26/Mar/2026:16:47:33 +0000] "GET /?id=5&page=test&test=100 HTTP/1.1" 200 615 "-" "curl/8.11.1" "172.21.0.1"

Unexpected, query field id gone

# curl -k -v --connect-to test.dev:443:127.0.0.1:8443 'https://test.dev/?page=test&id=5&test=100'
node1-1  | 172.21.0.2 - - [26/Mar/2026:16:56:26 +0000] "GET /?page=test&test=100 HTTP/1.1" 200 615 "-" "curl/8.11.1" "172.21.0.1"

Assistance Disclosure

AI not used

If AI was used, describe the extent to which it was used.

No response

[steadytao]

Will look into this.