_error_string_n(unsigned long e, char *buf, size_t len);

const char *ERR_lib_error_string(unsigned long e);
const char *ERR_reason_error_string(unsigned long e);</code></pre>

<p>Deprecated in OpenSSL 3.0:</p>

<pre><code>const char *ERR_func_error_string(unsigned long e);</code></pre>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>ERR_error_string() generates a human-readable string representing the error code <i>e</i>, and places it at <i>buf</i>. <i>buf</i> must be at least 256 bytes long. If <i>buf</i> is 