---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_ERRORBUFFER
Section: 3
Source: libcurl
See-also:
  - CURLOPT_DEBUGFUNCTION (3)
  - CURLOPT_VERBOSE (3)
  - curl_easy_strerror (3)
  - curl_multi_strerror (3)
  - curl_share_strerror (3)
  - curl_url_strerror (3)
Protocol:
  - All
Added-in: 7.1
---

# NAME

CURLOPT_ERRORBUFFER - error buffer for error messages

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_ERRORBUFFER, char *buf);
~~~

# DESCRIPTION

Pass a char pointer to a buffer that libcurl may use to store human readable
error messages on failures or problems. This may be more helpful than the
single return code from curl_easy_perform(3) and related functions. The buffer
must be at least **CURL_ERROR_SIZE** bytes big.

You must keep the associated buffer available until libcurl no longer needs
it. Failing to do so might cause odd behavior or even crashes. libcurl might
need it until you call curl_easy_cleanup(3) or you set the same option again
to use a different pointer.

libcurl initializes the contents of the error buffer to an empty string before
performing a transfer.

Do not attempt to set the contents of the buffer yourself, including in any
callbacks you write that may be called by libcurl. The library may overwrite
the buffer after your callback returns.

Consider CURLOPT_VERBOSE(3) and CURLOPT_DEBUGFUNCTION(3) to better debug and
trace why errors happen.

Using this option multiple times makes the last set pointer override the
previous ones. Set it to NULL to disable its use again.

# DEFAULT

NULL

# %PROTOCOLS%

# EXAMPLE

~~~c
#include <string.h> /* for strlen() */
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    char errbuf[CURL_ERROR_SIZE];

    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

    /* provide a buffer to store errors in */
    curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errbuf);

    /* set the error buffer as empty before performing a request */
    errbuf[0] = 0;

    /* perform the request */
    result = curl_easy_perform(curl);

    /* if the request did not complete correctly, show the error
       information. if no detailed error information was written to errbuf
       show the more generic information from curl_easy_strerror instead. */
    if(result != CURLE_OK) {
      size_t len = strlen(errbuf);
      fprintf(stderr, "\nlibcurl: (%d) ", (int)result);
      if(len)
        fprintf(stderr, "%s%s", errbuf,
                ((errbuf[len - 1] != '\n') ? "\n" : ""));
      else
        fprintf(stderr, "%s\n", curl_easy_strerror(result));
    }
  }
}
~~~

# HISTORY

Before curl 7.60.0, if an error code was returned but there was no error
detail the buffer was untouched: not initialized.

# %AVAILABILITY%

# 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).
