Express server with express-fileupload

The idea is to upload files to an express server keeping the original name.

HTML form

<form action="/procesar" method="post">
    <div class="form-group">
        <label for="exampleFormControlFile1">Cargar archivo nuevo</label>
        <input type="file" class="form-control-file" id="FormControlFile1" name="FormControlFile1">
    </div>
    <div class="form-group">
        <button type="submit" class="btn btn-primary mb-2">Procesar</button>
        <button type="button" class="btn btn-danger mb-2" id="uno">Eliminar</button>
    </div>
</form>

servers

router.post('/procesar', (req, res) => {
    if (!req.files || Object.keys(req.files).length === 0) {
        return res.status(400).send('No files were uploaded.');
    }

    // The name of the input field is used to retrieve the uploaded file
    let FormControlFile1= req.files.FormControlFile1;

    // Use the mv() method to place the file somewhere on your server
    FormControlFile1.mv('/temp/file.txt', function (err) {
        if (err)
            return res.status(500).send(err);

        res.send('File uploaded!');
    });
});

===> express-fileupload Examples <===

When uploading a file.txt you get: No files were uploaded .