✊🏿 Black Lives Matter. Please consider donating to Black Girls Code today.
🐇 Announcing Dash VTK for 3d simulation graphics. Check out the March webinar.

Multi-page app not working after upgrading to Dash 1.12.0


I trying to create a multi-page app and I started with the examples from your documentation - first example in section Structuring a Multi-Page App: https://dash.plotly.com/urls

It was working until I upgraded to the latest version. Now it is returning:
html: “In the callback for output(s):\n page-content.children\nOutput 0 (page-content.children) is already in use.\nAny given output can only have one callback that sets it.\nTo resolve this situation, try combining these into\none callback function, distinguishing the trigger\nby using dash.callback_context if necessary.”

Any help will be appreciated since I really want to keep that version and take advantage of the suppress_callback_exceptions.


I am getting this same issue when using multiple URLs. Auto-redirecting from ‘/index’ to ‘/newpage’ while simultaneously writing the page-content. Any work around?

Update: I am able to re-direct automatically using the following code. The keythgin is to update dcc.Location, but that update is written to a temporary storage. Here in my case, as soon as iles are uploaded, I am checking if its a success and then re-directing to new url.

# Update page
    Output("temporary-store", "children"),
    [Input('upload-data', 'contents')])
def display_page(contents):
    if contents is not None:
        return dcc.Location(pathname="/newurl", id="something-id")

I did not manage to make that work, so I went for that: