imagick WriteImage function is not working using Php 7.4

I am trying to write images using imagick php extension but code break on write image line. I also comment this line in policy.xml

<!-- <policy domain="coder" rights="none" pattern="PDF" /> -->

I am trying this code

private $path;
private $file;

function __construct($file){
    $this->path = "upload/".$file;
    $this->file = $file;
}
function convertDocument(){

    if ( !is_dir("custom/modules/Contacts/temp") ) {
        mkdir("custom/modules/Contacts/temp",0777,TRUE);       
        chmod("custom/modules/Contacts/temp", 0777);
    }

    $imagick = new imagick();
    $imagick->setResolution(200, 200);
    $imagick->readImage($this->path);
    $imagick->setImageBackgroundColor('white');
    $imagick->setImageAlphaChannel(11);
    $GLOBALS['log']->fatal('Read Image');

    $imagick->setImageResolution(2000, 2000);

    $imagick->setImageFormat('jpg');
    $pages = (int)$imagick->getNumberImages();
    $GLOBALS['log']->fatal('Get Image Pages: '.$pages);

    foreach($imagick as $i=>$imagick) {    
        $GLOBALS['log']->fatal('Write Images '.$i);
        $imagick->writeImage("custom/modules/Contacts/temp/".$this->file."_".$i.".jpg");
    }

    $GLOBALS['log']->fatal('After Writing images, START MERGING');

    $mpdf = new mPDF('en','Letter');

    for($p = 0; $p < $pages; $p++){
        $GLOBALS['log']->fatal('Write Image in PDF '.$p);

        $mpdf->WriteHTML("<img src='custom/modules/Contacts/temp/".$this->file."_".$p.".jpg' />");
    }

    $mpdf->Output('custom/modules/Contacts/temp/'.$this->file.'.pdf');
    $imagick->clear();

    $GLOBALS['log']->fatal('Conversion End .... ');



    return;
}

Please help me how i can solve this issue.