xh receives 400 Bad Request with the default http-version

[recsubbu]

Hi,

Thanks for this wonderful tool.

macOS (Monterey)
python 3.13
uvicorn 0.34.0

$ xh -V
xh 0.25.0

uvicorn serves HTTP 1.1 well for browser requests.

INFO: 127.0.0.1:57380 - "GET / HTTP/1.1" 200 OK

But, xh gets a 400 bad request.

$ xh localhost:5001
HTTP/1.1 400 Bad Request
Connection: close
Content-Length: 30
Content-Type: text/plain; charset=utf-8
Date: Thu, 27 Nov 2025 11:05:53 GMT
Server: uvicorn

Invalid HTTP request received.

HTTP 1.0 is works fine.

$ xh --http-version 1 localhost:5001
HTTP/1.1 200 OK
Content-Length: 3254
Content-Type: text/html; charset=utf-8
Date: Thu, 27 Nov 2025 11:14:43 GMT
Server: uvicorn

Debug output:

$ xh --debug localhost:5001
[0.000020s DEBUG xh] xh 0.25.0 -native-tls +rustls
[0.000071s DEBUG xh] Cli {
httpie_compat_mode: false,
json: false,
form: false,
multipart: false,
raw: None,
pretty: None,
format_options: [],
style: None,
response_charset: None,
response_mime: None,
print: None,
headers: false,
body: false,
meta: false,
verbose: 0,
debug: true,
all: false,
history_print: None,
quiet: 0,
stream_raw: false,
compress: 0,
stream: None,
output: None,
download: false,
resume: false,
session: None,
session_read_only: None,
is_session_read_only: false,
auth_type: None,
auth: None,
bearer: None,
ignore_netrc: false,
offline: false,
check_status_raw: false,
check_status: None,
follow: false,
max_redirects: None,
timeout: None,
proxy: [],
verify: None,
cert: None,
cert_key: None,
ssl: None,
native_tls: false,
default_scheme: None,
https: false,
http_version: None,
resolve: [],
interface: None,
ipv4: false,
ipv6: false,
unix_socket: None,
ignore_stdin: false,
curl: false,
curl_long: false,
generate: None,
help: None,
raw_method_or_url: Some(
"localhost:5001",
),
raw_rest_args: [],
method: None,
url: Url {
scheme: "http",
cannot_be_a_base: false,
username: "",
password: None,
host: Some(
Domain(
"localhost",
),
),
port: Some(
5001,
),
path: "/",
query: None,
fragment: None,
},
request_items: RequestItems {
items: [],
body_type: Json,
},
bin_name: "xh",
}
[0.000238s DEBUG xh] Complete URL: http://localhost:5001/
[0.000261s DEBUG xh] HTTP method: GET
[0.560407s DEBUG reqwest::connect] starting new connection: http://localhost:5001/
[0.561567s DEBUG hyper_util::client::legacy::connect::http] connecting to [::1]:5001
[0.561881s DEBUG hyper_util::client::legacy::connect::http] connecting to 127.0.0.1:5001
[0.562092s DEBUG hyper_util::client::legacy::connect::http] connected to 127.0.0.1:5001
HTTP/1.1 400 Bad Request
Connection: close
Content-Length: 30
Content-Type: text/plain; charset=utf-8
Date: Thu, 27 Nov 2025 11:20:00 GMT
Server: uvicorn

Invalid HTTP request received.

-Subbu

[blyxxyz]

The uvicorn example app accepts xh requests on my machine. What is your server code like? Do you have server log messages?

[recsubbu]

Hi,

A sample one.

$ cat tst.py

from fasthtml.common import *

hdr = Head(
Script(src='htmx.min.js'),
Link(href='twind.css', rel='stylesheet'),
viewport
)

app, rt = fast_app(live=True, default_hdrs=False, hdrs=hdr)

layout = Div(
Div(
P('Preview', cls='-mt-6'),
cls='border border-emerald-300 max-md:mb-5'
),
Div(
P('Editor', cls='-mt-6 absolute right-0'),
cls='border border-rose-300 relative'
),
cls='grid md:grid-cols-2 px-10 gap-2 h-screen'
)

@rt
def index():
return Titled(
'Webso, Socketso',
cls='text-3xl text-blue-400 mb-10'
), layout()

serve()

$ xh :5001
HTTP/1.1 400 Bad Request
Connection: close
Content-Length: 30
Content-Type: text/plain; charset=utf-8
Date: Thu, 27 Nov 2025 13:17:38 GMT
Server: uvicorn

Invalid HTTP request received.

log:

$ python tst.py
Link: http://localhost:5001
INFO: Will watch for changes in these directories: ['/Users/subbu/py/apps/nidhi.v1/tmp']
INFO: Uvicorn running on http://0.0.0.0:5001 (Press CTRL+C to quit)
INFO: Started reloader process [61835] using WatchFiles
INFO: Started server process [61837]
INFO: Waiting for application startup.
INFO: Application startup complete.
INFO: ('127.0.0.1', 57828) - "WebSocket /live-reload" [accepted]
INFO: connection open
INFO: 127.0.0.1:57829 - "GET / HTTP/1.1" 200 OK
INFO: connection closed
INFO: 127.0.0.1:57829 - "GET / HTTP/1.1" 200 OK
INFO: ('127.0.0.1', 57830) - "WebSocket /live-reload" [accepted]
INFO: connection open
INFO: connection closed
INFO: 127.0.0.1:57829 - "GET /htmx.min.js HTTP/1.1" 200 OK
INFO: 127.0.0.1:57831 - "GET /twind.css HTTP/1.1" 200 OK
INFO: ('127.0.0.1', 57832) - "WebSocket /live-reload" [accepted]
INFO: connection open
INFO: 127.0.0.1:57831 - "GET / HTTP/1.1" 200 OK
WARNING: Invalid HTTP request received.
WARNING: Invalid HTTP request received.

[recsubbu]

Earlier, when Gemini looked at the debug output, it noticed a significant delay here. But, it could not help further.

This delay is not seen when py requests module makes a request to uvicorn @ localhost:5001

[0.000261s DEBUG xh] HTTP method: GET
[0.560407s DEBUG reqwest::connect] starting new connection: http://localhost:5001/

[blyxxyz]

Thanks for the script! Unfortunately the requests still succeed on my machine (Debian 13, Python 3.13).

@ducaale can you test it on macOS?

Here's the script again, reformatted with a PEP 723 header for uv:

#!/usr/bin/env -S uv run --script
# /// script
# requires-python = ">=3.13"
# dependencies = [
#     "python-fasthtml",
#     "uvicorn==0.34.0",
# ]
# ///

from fasthtml.common import *

hdr = Head(
    Script(src="htmx.min.js"), Link(href="twind.css", rel="stylesheet"), viewport
)

app, rt = fast_app(live=True, default_hdrs=False, hdrs=hdr)

layout = Div(
    Div(P("Preview", cls="-mt-6"), cls="border border-emerald-300 max-md:mb-5"),
    Div(
        P("Editor", cls="-mt-6 absolute right-0"), cls="border border-rose-300 relative"
    ),
    cls="grid md:grid-cols-2 px-10 gap-2 h-screen",
)


@rt
def index():
    return Titled("Webso, Socketso", cls="text-3xl text-blue-400 mb-10"), layout()


serve()

[ducaale]

I'm not able to reproduce the bug but it sounds similar to seanmonstar/reqwest#2687

@recsubbu can I confirm if you're using x86 or arm? You can share with us the output from uname -a

[blyxxyz]

Wow, that's a wild bug. I didn't expect it to go all the way down to LLVM: rust-lang/rust#140686 (comment), llvm/llvm-project#146068

Sidenote: if I'm reading the CI correctly the binaries are built with our MSRV (1.82), maybe building with a stable release would be better? (1.82 shouldn't have this bug though.)

[recsubbu]

Yes, I'm on x86. xh installed from macports.

$ uname -a
Darwin valuedev 21.6.0 Darwin Kernel Version 21.6.0: Mon Dec 19 20:44:01 PST 2022; root:xnu-8020.240.18~2/RELEASE_X86_64 x86_64

If my understanding is correct, this is a known issue and waiting for upstream changes. We are good to close.

Aliasing xh to xh --http-version 1 works around.

Thanks again.

[blyxxyz]

It's a compiler issue of all things, with a released fix. So I think you can fix it for yourself by making sure Rust and Cargo are up to date (at least 1.89, ideally 1.91.1 which is the latest stable) and then rebuilding/reinstalling xh. (Not sure how this works in Macports.)

Thanks for reporting! This was really interesting.

[recsubbu]

Welcome. Uninstalled macports version, did cargo binstall xh. All ok now.

$ xh :5001
HTTP/1.1 200 OK
Content-Length: 3254
Content-Type: text/html; charset=utf-8
Date: Fri, 28 Nov 2025 11:09:24 GMT
Server: uvicorn

Uvicorn end:

INFO:     127.0.0.1:58277 - "GET / HTTP/1.1" 200 OK