New version of dash-renderer causes "fetch not found" error in IE11 when redirecting user via callback

Maybe I’m doing something horribly wrong, I’m trying to redirect the user under certain circumstances, this code was working in IE11 fine until I updated dash.

On the following versions (installed via conda-forge) I don’t see the bug:

  • dash=0.26.6=py_0
  • dash-core-components=0.28.3=py_0
  • dash-html-components=0.12.0=py_0
  • dash-renderer=0.13.2=py_0
  • plotly=3.3.0=py37h28b3542_0

On the following versions I do see the bug:

  • dash=0.28.2=py_0
  • dash-core-components=0.33.0=py_0
  • dash-html-components=0.13.2=py_0
  • dash-renderer=0.14.1=py_0
  • plotly=3.3.0=py37h28b3542_0

Here is simplest version of the code to reproduce the bug:

import dash
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash(__name__)
app.css.config.serve_locally = True
app.scripts.config.serve_locally = True

app.layout = html.Div([
    dcc.Location(refresh=True, id='URL_OUT'),
    dcc.Location(refresh=False, id='URL_IN')

external_url = ''

@app.callback(output=dash.dependencies.Output('URL_OUT', 'href'),
              inputs=[dash.dependencies.Input('URL_IN', 'pathname')])
def login_callback(pathname):
    return external_url

if __name__ == '__main__':
    app.run_server(port=8050, host='')

Let me know if I’m doing something horribly wrong, this is a known bug, or I should report it somewhere specific. In both cases it executes fine in Chrome.

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Seems this was the same error: On IE11 getting error SCRIPT5009: 'fetch' is undefined

And was fixed with dash-renderer-0.14.3:

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