System Error/Success messages are not displaying in custom theme

Question

I have created a simple custom theme which has dependency on Magento/blank

Everything in my theme works good except that whenever I add any error/success messages to the messageManager in my custom module and do a redirect to the custom page displaying a form.

It doesn't display those messages.

What I Did

\Magento\Framework\Message\ManagerInterface $messageManager is injected in the constructor

$this->messageManager->addError('Invalid details provided.'); added this in my controler action's execute method

$this->_redirect('myorders/uploadorder/index'); doing a redirect to the page where the form is displayed

What I have already refereed in stack exchange

Magento 2 : success messages are not showing

How to use messageManager to show an error after redirect

Magento 2: Ensure Message Manager Messages Show Up After a Redirct

Answer 1

From what I can see with what your posting it doesn't seem to be an issue with the functional more the theme or 3rd party extension removing the message block or you have a js conflict which is preventing it

In my case it was a 3rd party application causing a it to reset the message cookie check in chome cookies and see if the response is being set and reset if so it's most likely a module which is causing the message to be unset

Answer 2

In your controller execute action:

/** @var \Magento\Framework\Controller\Result\Redirect $resultRedirect */
$resultRedirect = $this->resultRedirectFactory->create();
$this->_messageManager->addErrorMessage(__('Some error message.'));

$resultRedirect->setPath('your/module/path');

return $resultRedirect;

Answer 3

 protected $_messageManager;

public function __construct(        
    \Magento\Framework\Message\ManagerInterface $messageManager, 
  ) {   

           $this->messageManager = $messageManager; 
           return parent::__construct($context);

      }

    public function execute()   {

        if(/* set your condition */)
        {

              $this->messageManager->addSuccessMessage(__('Subscriber succesfully  done'));

        }else{

             $this->messageManager->addErrorMessage(__('Already Subscriber'));
        }

        $resultRedirect = $this->resultRedirectFactory->create();
        $resultRedirect->setPath('/');
        return $resultRedirect;

    }