{% block style %}
{{ dropzone.load_css() }}
{{ dropzone.style('border: 2px dashed #0087F7; margin: 10%; min-height: 400px;') }}
{% endblock %}

{% block scripts %}
<script src="{{url_for('static', filename='jsfiles/dropzone.js')}}"></script>
{% endblock %}

{{ dropzone.create(action=url_for('folder1.upload, id=user.id'))}}
{{ dropzone.load_js() }}
{{ dropzone.config() }}

@inspection.route('/users/<int:user__id>', methods=['GET', 'POST'])
def upload(id):
    //Some Code
    if form.validate_on_submit() and 'photo' in request.files:
      for f in request.files.getlist('photo'):
         filename = secure_filename(f.filename)
         print(filename)

    return render_template('folder/user_details.html.j2')

Cannot build url for endpoint folder1.upload