diff --git a/features/file-upload.xml b/features/file-upload.xml
index 1b8b2fe461..30e219b1ce 100644
--- a/features/file-upload.xml
+++ b/features/file-upload.xml
@@ -326,7 +326,10 @@ foreach ($_FILES["pictures"]["error"] as $key => $error) {
        <term><constant>UPLOAD_ERR_EXTENSION</constant></term>
        <listitem>
          <para>
-           Value: 8; File upload stopped by extension. Introduced in PHP 5.2.0.
+           Value: 8; A PHP extension stopped the file upload. PHP does not 
+           provide a way to ascertain which extension caused the file upload to 
+           stop; examining the list of loaded extensions with phpinfo() may help. 
+           Introduced in PHP 5.2.0.
          </para>
        </listitem>
      </varlistentry>