Cannot redirect to a specific page using Observer events such as sales_order_place_before, and checkout_submit_before in Magento 2.3

Question

I am currently implementing a behavior where I will check the quote items in cart, then check if it contains my custom attributes. If true, then it will redirect me to a specific page(CMS) page.
This behavior should trigger before place order is processed.

I already tried using, observer events: sales_order_place_before and checkout_submit_before. I was not successful in implementing the redirect in the observer. The place order process seems to ignore redirects from the observer.

Here is my code:

app/code/Package/ModuleName/etc/events.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
<event name="sales_order_place_before">
    <observer name="observer_name" instance="Package\ModuleName\Observer\BeforePlaceOrder"/>
</event>

app/code/Package/ModuleMame/Observer/BeforePlaceOrder.php

 public function execute(Observer $observer)
{
    $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
    /** @var \Magento\Framework\UrlInterface $url */
    $url = $objectManager->create('\Magento\Framework\UrlInterface');

    /** @var \Magento\Framework\App\ResponseInterface $response */
    $response = $objectManager->create('\Magento\Framework\App\ResponseInterface');

    $customerBeforeAuthUrl = $url->getUrl('support-plan-option'); //you can change the routh path to your cms page
    $response->setRedirect($customerBeforeAuthUrl)->sendResponse();
}

Answer 1

Try using the following in your constructor:

• \Magento\Framework\App\ResponseFactory to set the redirection and

• \Magento\Framework\UrlInterface to set the URL to redirect.

Answer 2

You can simply use this code in your observer to redirect on any specific page.

protected $_redirect;

protected $_actionFlag;

public function __construct(
    \Magento\Framework\App\Response\RedirectInterface $redirect,
    \Magento\Framework\App\ActionFlag $actionFlag
) {
    $this->_redirect = $redirect;
    $this->_actionFlag = $actionFlag;
}

public function execute(Observer $observer)
{
    $this->_actionFlag->set('', \Magento\Framework\App\Action\Action::FLAG_NO_DISPATCH, true);
    $this->_redirect->redirect($controller->getResponse(), 'support-plan-option');
}

Hope this may help you. :)