CURLOPT_HTTP09_ALLOWED - allow HTTP/0.9 response

Added in curl 7.64.0

0

Pass the long argument allowed set to 1L to allow HTTP/0.9 responses. An HTTP/0.9 response is a server response entirely without headers and only a body. You can connect to lots of random TCP services and still get a response that curl might consider to be HTTP/0.9.

int main(void) { CURL *curl = curl_easy_init(); if(curl) { CURLcode ret; curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/"); curl_easy_setopt(curl, CURLOPT_HTTP09_ALLOWED, 1L); ret = curl_easy_perform(curl); } }

curl allowed HTTP/0.9 responses by default before 7.66.0 Since 7.66.0, libcurl requires this option set to 1L to allow HTTP/0.9 responses.

CURLOPT_HTTP09_ALLOWED - allow HTTP/0.9 response

This functionality affects http only

curl_easy_setopt(3) returns a CURLcode indicating success or error. CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors(3).

CURLOPT_HTTP_VERSION(3), CURLOPT_SSLVERSION(3) libcurl 2025-06-16 CURLOPT_HTTP09_ALLOWED(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTP09_ALLOWED, long allowed);