Error saving a PDF with FPDF php

When I try to save a pdf to the server I get the following message:

FPDF error: Incorrect output destination: C: \ XAMPP \ HTDOCS \ MYPROYECT \ PUBLIC \ SYSTEM \ APP \ CONTROLLERS /../../ PUBLIC / FILES / PDF / POLIZA_5B7B44F8AF44A.PDF

  

Now try to view the pdf in the browser using   $ pdf-> Output (); and he shows it to me without any problem, but when   I want to save to the server with $ pdf-> Output ('F', $ file); do not   It works.

$pdf=new PDF_MC_Table();
$pdf->AddPage('L');
$pdf->SetFont('Arial','',10);
$pdf->SetWidths(array(20,20,20));
$pdf->Row(array('Dato 1','Dato 2', 'Dato 3'));

$file =  __DIR__  . "/../../public/archivos/pdf/";
@mkdir($file,0750);
$nombre = uniqid('poliza_').'.pdf';
$file .= $nombre;
$pdf->Output('F', $file );
// mi clase para crear las filas
class PDF_MC_Table extends FPDF{
    var $widths;
    var $aligns;

    function SetWidths($w)
    {
        //Set the array of column widths
        $this->widths=$w;
    }

    function SetAligns($a)
    {
        //Set the array of column alignments
        $this->aligns=$a;
    }

    function Row($data)
    {
        //Calculate the height of the row
        $nb=0;
        for($i=0;$i<count($data);$i++)
            $nb=max($nb,$this->NbLines($this->widths[$i],$data[$i]));
        $h=5*$nb;
        //Issue a page break first if needed
        $this->CheckPageBreak($h);
        //Draw the cells of the row
        for($i=0;$i<count($data);$i++)
        {
            $w=$this->widths[$i];
            $a=isset($this->aligns[$i]) ? $this->aligns[$i] : 'L';
            //Save the current position
            $x=$this->GetX();
            $y=$this->GetY();
            //Draw the border
            $this->Rect($x,$y,$w,$h);
            //Print the text
            $this->MultiCell($w,5,$data[$i],0,$a);
            //Put the position to the right of the cell
            $this->SetXY($x+$w,$y);
        }
        //Go to the next line
        $this->Ln($h);
    }

    function CheckPageBreak($h)
    {
        //If the height h would cause an overflow, add a new page immediately
        if($this->GetY()+$h>$this->PageBreakTrigger)
            $this->AddPage($this->CurOrientation);
    }

    function NbLines($w,$txt)
    {
        //Computes the number of lines a MultiCell of width w will take
        $cw=&$this->CurrentFont['cw'];
        if($w==0)
            $w=$this->w-$this->rMargin-$this->x;
        $wmax=($w-2*$this->cMargin)*1000/$this->FontSize;
        $s=str_replace("\r",'',$txt);
        $nb=strlen($s);
        if($nb>0 and $s[$nb-1]=="\n")
            $nb--;
        $sep=-1;
        $i=0;
        $j=0;
        $l=0;
        $nl=1;
        while($i<$nb)
        {
            $c=$s[$i];
            if($c=="\n")
            {
                $i++;
                $sep=-1;
                $j=$i;
                $l=0;
                $nl++;
                continue;
            }
            if($c==' ')
                $sep=$i;
            $l+=$cw[$c];
            if($l>$wmax)
            {
                if($sep==-1)
                {
                    if($i==$j)
                        $i++;
                }
                else
                    $i=$sep+1;
                $sep=-1;
                $j=$i;
                $l=0;
                $nl++;
            }
            else
                $i++;
        }
        return $nl;
    }
}