게시글(글쓰기) 작성 시 작성완료 버튼 클릭하면 화면이 안나와요 채택완료

게시글 작성 시(글쓰기) 작성완료버튼을 누르면 /write_update.php 로 넘어가면서

화면이 비어져 나오는데요.

폴더에 write_update.php 자체가 없는데요. 

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<div class="btn_confirm">
    <input type="submit" value="작성완료" id="btn_submit" accesskey="s" class="btn_submit">
    <a href="./board.php?bo_table=<?php echo $bo_table ?>" class="btn_cancel">취소</a>
</div>

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<!-- 게시물 작성/수정 시작 { -->
<form name="fwrite" id="fwrite" action="<?php echo $action_url ?>" onsubmit="return fwrite_submit(this);" method="post" enctype="multipart/form-data" autocomplete="off" style="width:<?php echo $width; ?>">
    <input type="hidden" name="uid" value="<?php echo get_uniqid(); ?>">
    <input type="hidden" name="w" value="<?php echo $w ?>">
    <input type="hidden" name="bo_table" value="<?php echo $bo_table ?>">
    <input type="hidden" name="wr_id" value="<?php echo $wr_id ?>">
    <input type="hidden" name="sca" value="<?php echo $sca ?>">
    <input type="hidden" name="sfl" value="<?php echo $sfl ?>">
    <input type="hidden" name="stx" value="<?php echo $stx ?>">
    <input type="hidden" name="spt" value="<?php echo $spt ?>">
    <input type="hidden" name="sst" value="<?php echo $sst ?>">
    <input type="hidden" name="sod" value="<?php echo $sod ?>">
    <input type="hidden" name="page" value="<?php echo $page ?>">

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이렇게 적용이되어 있는데 왜 저 파일로 넘어가는걸까요?