PHP echos file as text instead of binary on server - php

Question

I have written a PHP page which reads a file and does echo it after adding some headers:
header('Content-disposition: filename="' . $fname . '"');
header('Pragma: no-cache');
header('Expires: 0');
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Pragma: public');
header("Content-type: $AttachFileType");
header("Content-Transfer-Encoding: binary");
header("Content-Length: " . filesize($ffullname));
echo file_get_contents($ffullname);
This piece of code does well on local test, but when porting to the server, the response is not as expected. For example when I want to retrieve a png file, I get the below image on local test:
while server test outputs this one:
As I have investigated, the only difference of them is 4 additional headers on server response. Local test response headers:
Cache-Control: must-revalidate, post-check=0, pre-check=0
Connection: Keep-Alive
Content-disposition: filename="attachment_hrmstotal_generalskills_6.png"
Content-Length: 2401
Content-Transfer-Encoding: binary
Content-Type: png
Date: Wed, 23 May 2018 04:45:02 GMT
Expires: 0
Keep-Alive: timeout=5, max=97
Pragma: public
Server: Apache/2.4.27 (Ubuntu)
and server response headers are these:
Cache-Control: must-revalidate, post-check=0, pre-check=0
Connection: keep-alive
Content-disposition: filename="attachment_hrmstotal_generalskills_1.png"
Content-Length: 184450
Content-Transfer-Encoding: binary
Content-Type: png
Date: Wed, 23 May 2018 04:40:56 GMT
Expires: 0
Pragma: public
Server: nginx/1.8.0
Strict-Transport-Security: max-age=31536000
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
The last four headers is the difference. What is the problem, its reason and how to solve it?

Answer 1

Your content-type should be Content-type: image/png