<b>NULL</b>, the error string is placed in a static buffer. Note that this function is not thread-safe and does no checks on the size of the buffer; use ERR_error_string_n() instead.</p>

<p>ERR_error_string_n() is a variant of ERR_error_string() that writes at most <i>len</i> characters (including the terminating 0) and truncates the string if necessary. For ERR_error_string_n(), <i>buf</i> may not be <b>NULL</b>.</p>

<p>The string will have the following format:</p>

<pre><code>error:[error code]:[librar