标头未发送到用户浏览器进行下载

我有下载pdf等文件的脚本。。。。有些时候，当我点击下载它的链接时，工作并下载文件，有些时候，我点击下载链接时，会出现错误"header_sent=false"。我在php.ini中尝试了"关闭"buffer_output"answers"打开"，但问题相同。在设置标题之前也尝试过"ob_end_clean"，但没有成功。这里的问题头没有发送到用户浏览器，我不知道为什么。

我的php代码。

<?php
ob_start();
error_reporting(E_ALL);
$company =$_GET['company']; 
if(isset($_GET['id']))
{
$id = intval($_GET['id']);
if($id <= 0)
{
die('The ID is invalid!');
}
else
{
$dbLink = new mysqli('localhost', 'sqldata', 'sqldata', 'balhaf');
if(mysqli_connect_errno())
{
die("MySQL connection failed: ". mysqli_connect_error());
}
$query = "SELECT mime, name, size, data FROM $company WHERE id = $id";
$result = $dbLink->query($query);
if($result)
{
if($result->num_rows == 1) {
$row = mysqli_fetch_assoc($result);
if( headers_sent() )
{
die('Headers Sent');
}
else
{
echo "error";
}
var_dump(headers_sent());
header("Content-Type: application/force-download");
header("Content-Type: application/octet-stream");
header("Content-Type: application/download");
header("Cache-Control: ");
header("Pragma: ");
header("Content-Type: ". $row['mime']);
header("Content-Disposition: attachment; filename=". $row['name']);
header("Content-Length: ".$row['size']);
header('Expires: 0');
header('Accept-Ranges: bytes');
header("Cache-control: private");
header('Pragma: private');

echo $row['data'];
exit;
}
else {
echo 'Error! No image exists with that ID.';
}
@mysqli_free_result($result);
}
else
{
echo "Error! Query failed: <pre>{$dbLink->error}</pre>";
}
@mysqli_close($dbLink);
}
}
else
{
echo 'Error! No ID was passed.';
}
?>