kaggle can't create a web page using dash and vizro

Describe your context

using the latest version of www.kaggle.com

• replace the result of pip list | grep dash below

dash                                     2.18.1
dash_ag_grid                             31.2.0
dash-bootstrap-components                1.6.0
dash-core-components                     2.0.0
dash-html-components                     2.0.0
dash-mantine-components                  0.12.1
dash-table                               5.0.0

vizro                                    0.1.25

• if frontend related, tell us your Browser, Version and OS

  • OS: Linux Mint 21.3 Cinnamon 6.0.4 5.15.0-124-generic
  • Browser firefox 131.0.3 (64-bit)

Describe the bug

kaggle can't connect to local Dash app running on http://127.0.0.1:8050/

running code below in a kaggle notebook on linux mint ( ufw disabled) vpn turned off ( just in case),

it says it’s running BUT

running the cell I get

Dash app running on http://127.0.0.1:8050/

but either running tab or external I get

Unable to connect


Firefox can’t establish a connection to the server at 127.0.0.1:8050.

    The site could be temporarily unavailable or too busy. Try again in a few moments.
    If you are unable to load any pages, check your computer’s network connection.
    If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the web.

firewall is off

sudo ufw status Status: inactive

all the iptables are open

sudo iptables -L
Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source  

here’s the cell from kaggle

import pandas as pd
import vizro.models as vm
import vizro.plotly.express as px
from vizro import Vizro
from vizro.tables import dash_ag_grid

# Load the data from the CSV file
df = pd.read_csv('/kaggle/input/test_data.csv')

page = vm.Page(
    title="Testing vizro dash ag grid ",
    components=[
        vm.AgGrid(
            title="Test ag grid",
            figure=dash_ag_grid(
                data_frame=df
            )
        ),
    ],
    controls=[vm.Filter(column="Symbol")],
)

dashboard = vm.Dashboard(pages=[page])

Vizro().build(dashboard).run(jupyter_mode="external")

# Vizro().build(dashboard).run(jupyter_mode="tab")  # https://vizro.readthedocs.io/en/stable/pages/user-guides/run/#jupyter

# Vizro().build(dashboard).run(debug=False)

Expected behavior

On running the cells in kaggle I expect a webpage to be displayed

Screenshots

If applicable, add screenshots or screen recording to help explain your problem.

Start by reproducing the Kaggle notebook example using Vizro().build(dashboard).run(jupyter_mode="external"), then compare it with the commented tab and debug modes. Review the linked Stack Overflow report and the Dash issue context to determine whether the failure is in Dash, Vizro, or Kaggle's local web-app handling; done means the supported execution path is identified and documented or the responsible behavior is fixed.