PHP- file uploading working on localhost but not in server (linux) - php

Question

Upload file not working on server but it is working on localhost. File upload permission is ON, but even getting error. I tried all the solution over internet.
Here is my code.
if($submit == "UPLOAD PROFILE PICTURE") {
$user = $_COOKIE['userId'];
$file_name = $_FILES['userPic']['name'];
$file_size =$_FILES['userPic']['size'];
$file_tmp =$_FILES['userPic']['tmp_name'];
$file_type=$_FILES['userPic']['type'];
$tmp = explode('.', $file_name);
$file_ext = end($tmp);
$expensions= array("jpeg","jpg","png");
$nameToStore = $user.".".$file_ext;
chmod("images/users-dp/$nameToStore",0777);
if(in_array($file_ext,$expensions)=== true){
if($file_size < 2097152){
if(move_uploaded_file($file_tmp,"images/users-dp/".$nameToStore)) {
$queryFoCheck = "SELECT * FROM profilepic WHERE user = '$user'";
$resultFoCheck = $connection -> query($queryFoCheck);
$countFoCheck = mysqli_num_rows($resultFoCheck);
if($countFoCheck>=1) {
$query = "UPDATE profilepic SET piclink = '$nameToStore' WHERE user = '$user'";
$result = $connection -> query($query);
} else {
$query = "INSERT INTO profilepic VALUES ('$user', '$nameToStore') ";
$result = $connection -> query($query);
}
header('Location: profile.php?s'); //successsfully updated
} else {
header('Location: profile.php?e=1'); //Cant update
}
} else {
header('Location: profile.php?e=2'); //Cant update
}
} else {
header('Location: profile.php?e=3'); //Cant update
}
}