id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2564	nginx returns 501 when 400 is expected	bjorn248@…		"nginx seems to be exhibiting unexpected behavior when sending an invalid value for the Transfer-Encoding header.

I've been using the nginx docker container to test with locally:
docker run -p 8080:80 nginx

The following curl request results in an HTTP 501:

curl -I -X POST -H ""Transfer-Encoding: invalid"" localhost:8080

According to https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Transfer-Encoding there are only 4 valid values for the Transfer-Encoding header. If a client sends an invalid value, I'd expect the server to respond with an HTTP 400. nginx responds with an HTTP 501."	defect	closed	minor	nginx-1.26	nginx-core	1.25.x	invalid		bjorn248@…	Linux 5c6ed1f9df74 6.4.16-linuxkit #1 SMP PREEMPT_DYNAMIC Wed Oct 25 15:08:07 UTC 2023 x86_64 GNU/Linux	"nginx version: nginx/1.25.3
built by gcc 12.2.0 (Debian 12.2.0-14)
built with OpenSSL 3.0.9 30 May 2023 (running with OpenSSL 3.0.11 19 Sep 2023)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-http_v3_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-g -O2 -ffile-prefix-map=/data/builder/debuild/nginx-1.25.3/debian/debuild-base/nginx-1.25.3=. -fstack-protector-strong -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fPIC' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -Wl,--as-needed -pie'"