CURLOPT_FAILONERROR(3)

💖 CURLOPT_FAILONERROR(3) 💖 — Library Functions Manual

okay so bestie, this is the Library Functions Manual page for CURLOPT_FAILONERROR — the libcurl option that's literally about "request failure on HTTP response >= 400". no cap, it's giving "if the server says it's a problem, we believe it" energy. 💅✨

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🎀 NAME 🎀

CURLOPT_FAILONERROR — request failure on HTTP response >= 400 🫶

✨ SYNOPSIS ✨

here's the signature, bestie:

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_FAILONERROR, long fail);

🦋 DESCRIPTION 🦋

A long parameter set to 1 tells the library to fail the request if the HTTP code returned is equal to or larger than 400. The default action would be to return the page normally, ignoring that code. 💀

This method is not fail-safe, and there are occasions where non-successful response codes slip through, especially when authentication is involved (response codes 401 and 407). 🙈 like, it's trying its best but it's not a guarantee.

You might get some amounts of headers transferred before this situation is detected, like when a "100-continue" is received as a response to a POST/PUT and a 401 or 407 is received immediately afterwards.

⚠️ when this option is used and an error is detected, it causes the connection to get closed and CURLE_HTTP_RETURNED_ERROR is returned. that's the whole mood — connection says bye and the error code says hi. 😭

🍓 DEFAULT 🍓

0, do not fail on error. so by default it's like "show me the page anyway, bestie." 🫠

🌈 PROTOCOLS 🌈

This functionality affects http only. that's the whole menu, iykyk. ⭐

👑 EXAMPLE 👑

okay, example time — here's the code:

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_FAILONERROR, 1L);
    result = curl_easy_perform(curl);
    if(result == CURLE_HTTP_RETURNED_ERROR) {
      /* an HTTP response error problem */
    }
  }
}

⭐ AVAILABILITY ⭐

Added in curl 7.1. vintage but still iconic. 🎀

💜 RETURN VALUE 💜

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). periodt. ✨

🔥 SEE ALSO 🔥

• CURLINFO_RESPONSE_CODE(3)
• CURLOPT_HTTP200ALIASES(3)
• CURLOPT_KEEP_SENDING_ON_ERROR(3)

go read these next, bestie, they're lowkey relevant. 🦋

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💖 source/version: libcurl · date: 2026-10-12 — bestie out! 💖