<html>

<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title></title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js"></script>
</head>

<body>
<!--Main container-->
<div class="container bg-light">
    <div class="row">
        mein Content
    </div>
        
    <div class="row">

        <form class="form-horizontal" action="" method="post" name="frmCSVImport" id="frmCSVImport" enctype="multipart/form-data">
            <div class="input-row">                
                <button type="button" class="btn btn-info" data-toggle="modal" data-target="#uploadModal">Upload Datei</button>
                <br />
            </div>
        </form>
    </div>

    <div class="row">
        <button type='submit' class="btn btn-info" onclick='uploadstatus()'>Test Button <b>AUßERHALB</b> Modal</button>
    </div>
</div>


<!-- Modal File Upload-->
<div id="uploadModal" class="modal fade" role="dialog">
    <div class="modal-dialog">
        <!-- Modal content-->
        <div class="modal-content">
        
            <div class="modal-header">
                <h4 class="modal-title">File upload form</h4>
                <button type="button" class="close" data-dismiss="modal">&times;</button>
            </div>
            
            <div class="modal-body">
                <!-- Form -->
                <form method='post' action='' enctype="multipart/form-data">
                    <!-- MAX_FILE_SIZE muss vor dem Dateiupload Input Feld stehen -->
                    <input type="hidden" name="MAX_FILE_SIZE" value="30000" />
                    Select file : <input type='file' name='file' id='file' class='form-control' accept=".csv" ><br>
                    <button type="button" class="btn btn-light" data-dismiss="modal">Cancel</button>
                    <button type='submit' class='btn btn-info' name="import" value='Upload' id='btn_upload'>Upload</button>
                    
                    <button type='submit' class="btn btn-danger" onclick='uploadstatus()'>Test Button <b>INNERHALB</b> Modal</button>

                </form>

                <!-- Preview-->
                <div id='preview'></div>
            </div>
    
        </div>
    </div>
</div>
<!-- END -- Modal -->
  </body>
</html>
function uploadstatus()
{
	var form_data = new FormData();                  
    form_data.append('file', file_data);
    alert(form_data);                        
	
   $.ajax({
        url: 'upload.php', // point to server-side PHP script 
        dataType: 'text',  // what to expect back from the PHP script, if anything
        cache: false,
        contentType: false,
        processData: false,
        data: form_data,                         
        type: 'post',
        beforeSend: function(){
            // zeige Spinner
            // $("#spinner").show();
            alert("Start");
        },
        success: function(result){
        },
        complete: function(){
            // Hide Spinner
            // $("#spinner").hide();
            alert("Ende");
        }
    });

};

External CSS

  1. https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css

External JavaScript

  1. https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js
  3. https://maxcdn.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js