Getting blank page and "Cannot read properties of undefined (reading 'map')" in JS

Hello guys,

Got a strange behaviour I no idea where to start adressing the issue.

I am using streamlit_option_menu for navigation (but I guess this may not be associated with the behaviour).

I got several pages. Two of my pages using st.tabs and st.expander. When I navigate between these two pages I sometimes get a blank page. Looking at JS console I can read the error message Cannot read properties of undefined (reading ‘map’) - which I guess comes from the React part?

This behavior only occurs when I navigate in one direction from page A to B but not the other way round. In addition, navigating to page B from any other page does also work without any probs.

May this error message be enough to give me any hint what is going wrong there?
Could it be associated with a too complex nested structure I use inside a st.expander?


Hi there,

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Caroline :balloon:

Hi Caroline,

Thank you for your hint. You are right, my message was quite unspecific. Problem is that I ought to share nearly the whole app to make the behavior reproducible. So I thought that maybe the JS error containing the term “map” could be an indication for a specific module or so.

In the meantime I figured out that this behavior only occurs in case I navigate to a different page when the current page is still processing (shows “running”).