Flash message is not displaying on ejs template

Question

I want to set an error message on ejs using flash. But my message is not displaying on the page. If I use the req.session.message, it's working perfectly. When an error occurs, I am redirecting it to another route. I can even access the flash message from there and log it to the console. It displays as an array. But its not displaying on ejs.

if (!catCombo) {
    req.flash('message','This category combination doesnot exist.')
    throw new Error("Category not found.");
// catch block...............................
} catch (error) {
    res.redirect('/admin/add-products')
}

//controller for /admin/add-products
const sendAddProducts = async (req, res) => {
    let message = req.flash('message');
    req.flash('message','');
    console.log(message)
    res.render("./admin/addProducts", { message, categories: catSet });
};

Using console.log(message) returns ['This category combination doesnot exists.']

On ejs side:

<% if(locals.message.length){ %>
    <div class="alert alert-danger" id="error-message"><%=message[0]%></div>
<% } %>

I entered message[0] since the console was shown as array. I even tried <%=message%\>. If I set the if condition just as locals.message, I can see the red colored div but not the message.

This is how did it on app.js:

const flash = require('connect-flash');
app.use(session({
    secret : uuidv4(),
    resave : false,
    saveUninitialized : true
}));
app.use(flash());