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<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs-project/">Documentation</a> &gt; <a href="../">Version 2.0</a> &gt; <a href="./">FAQ</a></div><div id="page-content"><div id="preamble"><h1>Error Messages - Frequently Asked Questions</h1></div>
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<h2><a name="error" id="error">Error Messages</a></h2>
    <ul>
    <li><a href="#error.sendfile">Invalid argument:
    core_output_filter: writing data to the network</a></li>
    </ul>

    <h3><a name="error.sendfile" id="error.sendfile">Invalid argument:
    core_output_filter: writing data to the network</a></h3>

    <p>Apache uses the <code>sendfile</code> syscall on platforms
    where it is available in order to speed sending of responses.
    Unfortunately, on some systems, Apache will detect the presence of
    <code>sendfile</code> at compile-time, even when it does not work
    properly.  This happens most frequently when using network or
    other non-standard file-system.</p>

    <p>Symptoms of this problem include the above message in the error
    log and zero-length responses to non-zero-sized files.  The
    problem generally occurs only for static files, since dynamic
    content usually does not make use of <code>sendfile</code>.</p>

    <p>To fix this problem, simply use the <code class="directive"><a href="../mod/core.html#enablesendfile">EnableSendfile</a></code> directive to disable
    <code>sendfile</code> for all or part of your server.  Also see
    the <code class="directive"><a href="../mod/core.html#enablemmap">EnableMMAP</a></code>, which can
    help with similar problems.</p>

    
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