json_encode return null and block code below

Question

I got stuck with a json_encode() problem in PHP.

The simple function below is trying to send the response data to an API call.

function makeResponseOK($data) {
    if($data) $response['data'] = $data;
    $response['meta'] = ['msg' => 'OK', 'status' => 200];
    header('Content-type: application/json');
    return json_encode($response, JSON_PRETTY_PRINT);
}     

It works perfectly fine on my MAC. However, when I tried to deploy it on my Ubuntu Server, json_encode() does not work at all and any line below json_encode() is neglected. For example:

echo 'crazy';
echo json_encode($data);
echo 'crazy';

will only output one "crazy" to me. I also tried:

echo json_last_error_msg();
echo json_last_error();
$arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
echo json_encode($arr);

but none of them give me any result, not even a number...

I have completely no idea what is going on there and I really appreciate if you could help me with it!!!

In addition: My Ubuntu Server's PHP version is 5.5.3 and I am using SLIM framework, idiorm.(Though I don't think it is related...)

Answer 1

Try to check if json_encode is actually available on your server. I know it should be there by default, but I ran into some servers where that function was not available.

if (function_exists('json_encode')) {
    echo 'Yes';
} else {
    echo 'No';
}

Answer 2

Here you have just used json use json_encode instead

$arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
echo json_encode($arr); // Here!
echo json_last_error_msg();
echo json_last_error();