Index of Multi-Page App not Rendering

Hey first post here.
I have a multi-page app that is hosted through Domino. When landing on the index page nothing loads and I get a 500 error for the _dash-update-component request. All of the other pages load when I navigate to the URL.

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

@app.callback(Output('page-content', 'children'),
              [Input('url', 'pathname')])
def display_page(pathname):
    if pathname == '/app1':
        return app1_layout
    elif pathname == '/app2':
        return app2_layout
    elif pathname == '/app3':
        return app3_layout
    elif pathname == '/app4':
        return app4_layout
        return index_layout```

Also, something of note. It worked fine locally - but when hosted on Domino I have this issue.

I would try and see if you can chase down the error logs. There will likely be some clues as to what’s throwing the exception.