FPDF - 无法将副本保存到文件系统

Question

我正在使用FPDF生成PDF文档。我想将副本保存到文件系统以获取我们的记录，并将用户的副本输出到浏览器。由于某种原因，我无法将文件保存到文件系统。任何人都可以看到它可能是什么？该文件夹的权限设置为777，因此不应该是问题。

        <?php 

    include('./fpdf181/fpdf.php'); 
    include('./FPDI-1.6.1/fpdi.php'); 

    //get user's name
    $name = $_GET['name'];

    // initiate FPDI 
    $pdf = new FPDI(); 
    // add a page 
    $pdf->AddPage(); 
    // set the sourcefile 
    $pdf->setSourceFile('../uploads/certificates/IBA-Certificate-Coaching-Course.pdf'); 
    // import page 1 
    $tplIdx = $pdf->importPage(1); 
    // use the imported page as the template 
    $pdf->useTemplate($tplIdx, 0, 0,210, 180, true); 

    // now write some text above the imported page 
    $pdf->SetFont('Arial','B',14);
    $pdf->SetTextColor(0,0,0); 

    //member's name
    $pdf->SetXY(88, 85); 
    $pdf->Write(0, $name); 

    //current date
    $date = date("m/d/Y");
    $pdf->SetXY(35, 140); 
    $pdf->Write(0, $date); 

    //save copy to file system
    $pdf->Output('./certificates/certificate-of-coaching-readiness.pdf','F');

    //output a copy to the user
    $pdf->Output('certificate-of-coaching-readiness.pdf', 'D'); 


    ?>