由于程序限制了大尺寸附件图片，提示 “没有合法的文件被上传”
更改方法：source\class\discuz\class_upload.php
找到：function get_image_info($target, $allowswf = false) {
                $ext = discuz_upload::fileext($target);
                $isimage = discuz_upload::is_image_ext($ext);
                if(!$isimage && ($ext != 'swf' || !$allowswf)) {
                        return false;
                } elseif(!is_readable($target)) {
                        return false;
                } elseif($imageinfo = @getimagesize($target)) {
                        list($width, $height, $type) = !empty($imageinfo) ? $imageinfo : array('', '', '');
                        $size = $width * $height;
                        if($size > 16777216 || $size < 16 ) {
                                return false;
                        } elseif($ext == 'swf' && $type != 4 && $type != 13) {
                                return false;
                        } elseif($isimage && !in_array($type, array(1,2,3,6,13))) {
                                return false;
                        }
                        return $imageinfo;
                } else {
                        return false;
                }
        }

将 if($size > 16777216 || $size < 16 )  中16777216更改大点