StreamLit: onProgress callback reruns app again and again

Steps to reproduce

Code snippet:

import streamlit as st
from backend import *
from streamlit_player import st_player
from time import sleep
from streamlit_extras.stoggle import stoggle
import os
import pickle

def get_questions_and_answers(url):
    video_id = get_video_id(url)
    cache_set = set(list(os.listdir("cache")))
    if video_id in cache_set:
        print("Loading from cache")
        response = pickle.load(open("cache/" + video_id, "rb"))
        return response
        transcript = get_transcript(url)
        chunks, chunk_time_stamps = parse_transcript_into_chunks(transcript)
        # ls_qna, chunk_time_stamps = get_placeholder_qna(chunks, chunk_time_stamps)
        ls_qna, chunk_time_stamps = get_question_and_answer(chunks, chunk_time_stamps)
        response = chunks, ls_qna, chunk_time_stamps
        # cache the response
        pickle.dump(response, open("cache/" + video_id, "wb"))
        return response

# Define the function for the Welcome Page
def welcome_page():
    st.session_state["page"] = "Welcome Page"
    st.title("Welcome Page")
    # Add an input box for the user to enter a value
    input_value = st.text_input("Enter a url:")
    # Add a button to compute the value and navigate to the Video Display Page
    if st.button("Compute and Go to Video Display Page"):
        # Display a spinner while the computation is in progress
        with st.spinner("Analyzing Video"):
            results = get_questions_and_answers(input_value)
        # Set the session state variables for the results and page
        st.session_state["results"] = results
        # save URL to session state
        st.session_state["url"] = input_value
        st.session_state["page"] = "Video Display Page"

# Define the function for the Video Display Page
def video_display_page():
    st.session_state["page"] = "Video Display Page"

    # Define session state variable
    if "is_playing" not in st.session_state:
        st.session_state.is_playing = False

    # Define callback functions
    def on_pause():
        print("Player is paused")
        st.session_state.is_playing = False
        st.write("Player is paused")

    def on_play():
        print("Player is playing")
        st.session_state.is_playing = True
        st.write("Player is playing")

    results = st.session_state.get("results")

    st.session_state.last_pause_time = 0 if st.session_state.get("last_pause_time", None) is None else st.session_state.last_pause_time

    st.title("Video Display Page")
    # 2 columns
    c1, c2 = st.columns([5, 3])

    with c2:
        playing_bool = False if st.session_state.get("playing_bool", None) is None else st.session_state.playing_bool
        st.session_state.playing_bool = playing_bool
        options = {
            # Onprogress is needed to get the time data
            "events": ["onPlay", "onPause", "onProgress"],
            "progress_interval": 500,
            "playing": st.checkbox("Playing", st.session_state.playing_bool),
            "controls": False,


    with c1:
        url = st.session_state.get("url")
        event = st_player(url, **options, key="youtube_player")

        if is not None and 'playedSeconds' in
            st.write("Time Played: ")
        # Check if player event was triggered
        if == "onPause" and st.session_state.playing_bool == True:
            print("onPause triggered")
            st.session_state.playing_bool = False
        elif == "onPlay" and st.session_state.playing_bool == False:
            print("onPlay triggered")
            st.session_state.playing_bool = True
        qnas = results[1]

# Define the main function
def main():
    # Initialize the session state
    if "page" not in st.session_state:
        print("Initializing session state")
        st.session_state["page"] = "Welcome Page"
    print("Current page:", st.session_state["page"])
    if st.session_state["page"] == "Welcome Page":
    elif st.session_state["page"] == "Video Display Page":

# Run the app
if __name__ == "__main__":

**Expected behavior: **

The app should not continously be reloading when the video is playing and also not throw the occasional KeyError: 'page' in the main() function

Actual behavior:

The app keeps reloading when the video is playing adding some print statements in the main() function show that it’s triggered repeatedly and I occasionally get a KeyError: Page in the second if condition or print statements in main() but that should never happen as if this is β€˜page’ was not there in the session state then it would’ve been added by the first if condition. The error comes up once in a while and the app just runs normally after that error once appears and then goes away. It seems as if the print or if conditions are triggered before session state is ready?

It seems this is caused by the onProgress callback. Is there somehow I can still use it but avoid this issue?

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