答案来自WordPress。组织支持论坛帖子：
；3.6 upgrade - searchform.php not working

像salcode 说：
将此代码添加到functions.php 应该做到：

function search_form_no_filters() {
  // look for local searchform template
  $search_form_template = locate_template( \'searchform.php\' );
  if ( \'\' !== $search_form_template ) {
    // searchform.php exists, remove all filters
    remove_all_filters(\'get_search_form\');
  }
}
add_action(\'pre_get_search_form\', \'search_form_no_filters\');

在WordPress 3.6中searchform.php 在您的主题中，仍由使用get_search_form(), 除非通过过滤掉get_search_form 钩

get\\u search\\u form（）中的示例代码：

$search_form_template = locate_template( \'searchform.php\' );
if ( \'\' != $search_form_template ) {
    ob_start();
    require( $search_form_template );
    $form = ob_get_clean();
} else {
    // compose the template, WordPress way
}

$result = apply_filters( \'get_search_form\', $form );
if ( null === $result )
    $result = $form;

if ( $echo )
    echo $result;
else
    return $result;