You can handle that by using try: and except: then write error message after the exception E,g : st.error("No file found") or st.text("No file found")

import streamlit as st

tab1, tab2, tab3 = st.tabs(["Cat", "Dog", "Owl"])

with tab1:
    st.header("A cat")
    try:
        st.image("_", width=200) # I changed here on purpose to raise an error
    except FileNotFoundError:
        st.text("File not found")

with tab2:
    st.header("A dog")
    try:
        st.image("", width=200)
    except FileNotFoundError:
        st.text("File not found")

with tab3:
    st.header("An owl")
    try:
        st.image("", width=200)
    except FileNotFoundError:
        st.text("File not found")

You can do same with functions that provide individual operations, since you said your first tab1 holds large data

import streamlit as st

tab1, tab2, tab3 = st.tabs(["Cat", "Dog", "Owl"])

def compute_tab1():
    st.header("A cat")
    try:
        st.image("_", width=200) # I changed here on purpose to raise an error
    except FileNotFoundError:
        st.text("File not found")


def compute_tab2():
    st.header("A dog")
    try:
        st.image("", width=200)
    except FileNotFoundError:
        st.text("File not found")

def compute_tab3():
    st.header("An owl")
    try:
        st.image("", width=200)
    except FileNotFoundError:
        st.text("File not found")

with tab1:
    compute_tab1()

with tab2:
    compute_tab2()

with tab3:
    compute_tab3()

Native solution

You can't do it with tabs. However, you can achieve a similar practical effect with st.radio() component.

import streamlit as st

animal = st.radio("Your animal:", ["Cat", "Dog", "Owl"])

if animal == "Cat":
    ...

External links

• Documentation

3rd party: Pills

However, from UI perspective, I'd recommend using a third-party library such as steramlit-pills:

pip install streamlit-pills

import streamlit as st
from streamlit_pills import pills

animal = pills("Your animal:", ["Cat", "Dog", "Owl"])

if animal == "Cat":
    st.header("A cat")
    st.image("_", width=200) # I changed here on purpose to raise an error

if animal == "Dog":
    st.header("A dog")
    st.image("", width=200)

if animal == "Owl":
    st.header("An owl")
    st.image("", width=200)

External links:

• Demo
• Documentation

3rd party: Antd

Another alternative would be Antd buttons

pip install streamlit-antd-components

import streamlit_antd_components as sac

animal = sac.buttons(['Cat', 'Dog', 'Owl'])

if animal == "Cat":
    ...

External links

• Demo
• Documentation