Receiving "error loading dependencies" message; actual problem is unclear

Here is a minimal example after doing some trial and error to pin it down:

#!/usr/bin/env python2
# -*- coding: utf-8 -*-

import dash
import dash_core_components as dcc
import dash_html_components as html


def generate_inputs():

    in_a_lab = html.Label('input a')
    in_a = dcc.Input(type='number',
                      value=1)
    
    in_b = [html.Label(html.Strong('input b')),
            dcc.Input(type='number', value=1)]

    inputs = [in_a_lab, in_a]

    # uncomment this line to cause error
    # inputs = [in_a_lab, in_a, in_b]

    return inputs

app = dash.Dash()
app.layout = html.Div([
    # switch the comment on these lines to cause an error
    html.Div(generate_inputs())
    # generate_inputs()
]) # app.layout


if __name__ == '__main__':
    app.run_server(debug=True)                        

I started on the path of python3, but ran into some dependency hell on Ubuntu 16.04, so I reinstalled with python2. This created what I believe to be some actual dependency issues around urllib3 and chardet. I was getting dependency warnings about the wrong versions on the command line when I would do python2 app.py.

With those solved, the command line looked fine, but I’d get this in the browser:

I was in the process of building some ui elements and doing them in pairs, with a label and then matching input. Then I wanted to switch to a list of the label and pair together. I realized I was sending back a nested list (the above would generated something like [in_a_lab, in_a, [in_b_lab, in_b]]). So, that was a definite issue, but I wouldn’t expect the result to be error loading dependencies.

On accident I found that without wrapping the function return in html.Div() I’m also getting the same error.

This is probably an issue on my part with something I don’t understand about dash (totally likely; I’m all of 2-3 hours into playing with it). That said, if this is isn’t really a “dependency error,” might there be room improving the error message? From what I’m seeing, this strikes me as more of a syntax error, or something like “expected blah object, got blah instead”?

Thanks for taking a look.

[jasper-muller]

I’m embarrassed to say that it turned out to be my ad blocker that was causing the problem.

Disabling ad block solved my issue.

[DBCerigo]

Just for anyone else googling out there: Another possible cause for the error might be that you have a circular cycle in your set of callbacks i.e. callbacks that trigger themselves in a loop (embarrassing…). Check JS console for something like Error: Dependency Cycle Found:....