Rocket.Chat/server/startup/migrations/v093.js

RocketChat.Migrations.add({
	version: 93,
	up() {

		if (RocketChat && RocketChat.models && RocketChat.models.Settings) {
			const setting = RocketChat.models.Settings.findOne({ _id: 'Accounts_AllowAnonymousAccess' });
			if (setting && setting.value === true) {
				RocketChat.models.Settings.update({ _id: 'Accounts_AllowAnonymousRead' }, { $set: { value: setting.value } });
			}
		}

		const query = {
			_id: {
				$in: [
					'view-c-room',
					'view-history',
					'view-joined-room',
					'view-p-room',
					'preview-c-room'
				]
			}
		};

		const update = {
			$addToSet: {
				roles: 'anonymous'
			}
		};

		RocketChat.models.Permissions.update(query, update, { multi: true });
	}
});