Why bot doesn't fire messageReactionAdd event when the message was sent before the bot was online

This is my event to check user add react:

const client = require("../index");

client.on('messageReactionAdd', async (reaction, user) => {
    if (user.bot) return;
    console.log(reaction.emoji.name);
});

It’s working, but when the bot restarts, it can’t fetch any message sent before?

Why and how to fix it?

>Solution :

You need partials:

const client = new Client({
    intents: ‘’, // your intents here
    partials: ['CHANNEL', 'GUILD_MEMBER', 'GUILD_SCHEDULED_EVENT', 'MESSAGE', 'REACTION', 'USER'],
});