PHP file upload works on Windows but not Linux

I am making a website that takes an audio file that is uploaded from a user, mixes it on my server and downloads it back to the users device, but it won't upload the file anymore. Initially I was running the website on my windows server but it for some reason struggled with getting the SSL certificate, so I had to build it from the ground up on Linux RHE.
To simplify the issue, I got a bare-bone file uploading script which also worked on my Windows port, but not on this server. The only response I got was "Error moving the uploaded file!", meaning something to do with the /tmp directory I assume and not being able to move it from there? I did look in the directory and it was pretty much empty, not the uploaded files. Here is the code.

`<?php
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Check if the file was uploaded without errors
    if (isset($_FILES['file']) && $_FILES['file']['error'] === UPLOAD_ERR_OK) {
        // Get the temporary filename
        $tempFile = $_FILES['file']['tmp_name'];
        $targetDir = '/var/www/html/';
        $targetFile = $targetDir . basename($_FILES['file']['name']);
    
        if (move_uploaded_file($tempFile, $targetFile)) {
            echo 'File uploaded and moved successfully.'; //I get this error
        } else {
            echo 'Error moving the uploaded file.';
        }
    } else {
        echo 'Error uploading file. Error code: ' . $_FILES['file']['error'];
    }
}
?>

<form method="POST" enctype="multipart/form-data">
    <input type="file" name="file">
    <button type="submit">Upload</button>
</form>`

I tested the same code on windows (with different directories of course) and it worked. I changed the permissions in the /tmp directory, chown, chmod.. I have made it print errors with $_FILES['file']['error'] which returned "0", meaning no error.

The expected outcome should be a "file uploaded successfully" and the file uploads to the websites directory for the other code to mix it.

It is possible that the problem is in the destination path, we must modify the permissions of
/var/www/html/ too

Another possible problem is that you are using the original file name, which can cause an error if there is already a file with the same name.