File download issue

Need Help
1 
$file_name = "m_files1.zip";
$fullPath = WWW_ROOT . 'zip_files' . DS . $file_name;
if (file_exists($fullPath)) {
            echo "<br>Found";
            return $this->response
                            ->withHeader('Content-Type', $mime)
                            ->withHeader('Content-Transfer-Encoding', 'Binary')
                            ->withHeader('Content-Disposition', 'attachment;filename="' . $file_name . '"')
                            ->withHeader('Content-Description', 'File Transfer')
                            ->withHeader('Cache-Control', 'must-revalidate, post-check=0, pre-check=0')
                            ->withHeader('Cache-Control', 'public')
                            ->withHeader('Expires', '0')
                            ->withHeader('Pragma', 'public')
                            ->withHeader('Content-Length', filesize($fullPath))
                            ->withFile(
                                    $fullPath,
                                    array('download' => true, 'name' => $file_name)
            );
        }

Don’t why after download zip file not open.

But if i download through direct file link, then that zip open perfectly.

what is the issue, please help me to fix.
I’m using cakephp3.8 .

2

Echoing something here is going to mess up the sending of headers. Don’t know if that will cause the problem you’re seeing, but it sure won’t help.

3

Yup. Check that actual file downloaded - I wouldn’t be surprised if the echo <br>found was the first bytes in the file.
Even having a carriage return a the end can break it. For instance if you made just a simple php which downloaded a file by setting the header then sending the data, then close the php with a ?> that alone can corrupt the download.

4

After remove echo issue fixed.
Thanks.