magento

Go to Admin => Stores > Configuration > Catalog > Catalog > Recently Viewed/Compared Products select Yes to ( Synchronize widget products with backend storage )
 

Unable to save address. Please check input data.

It's a strange error we have it sometime, to solve it in some cases you execute this query 

SELECT entity_id, customer_id FROM quote WHERE customer_id != 0 AND customer_is_guest = 1;

and then update the records by this query 

UPDATE quote SET customer_is_guest = 0 WHERE customer_id != 0 AND customer_is_guest = 1;

reference url :

https://stackoverflow.com/a/58086757/4135373

the best way is to work on your custom theme by modifying these files

/app/design/frontend/{Vendor}/{theme}/Magento_Checkout/layout/checkout_index_index.xml

To do this we need to work on the design area it is the easiest way 

firs Create new folder under your theme 

Folder Name: Magento_ConfigurableProduct\web\js

Copy this file "configurable.js" from this path

vendor/magento/module-configurable-product/view/frontend/web/js/configurable.js 

in the line 407 you need to modify this part

In this wiki we will find a way to use "==" equal in the email template, actually there is no equal in the email template itself but we can refer to a phtml file and pass a variable to it then use the if/equal in the phtml file to do this you can easily add this code to the template 

in the below example we will check if the payment method is bank transfer then we will write something

You need to use this in your constructer 

/**
 * @var Magento\Framework\Registry
 */
private $registry;

public function __construct(\Magento\Framework\Registry $registry)

{
    $this->registry = $registry;
}

then you can get the current category by this code

$category = $this->registry->registry('current_category');

you need to disable all these modules 

Magento include a base .gitignore file with the Magento Open Source project repository. See the latest Magento .gitignore file. If you need to add a file that is in the .gitignore list, you can use the -f (force) option when staging a commit:

Caching plays an essential role in improving the page load time. In this article, I want to show you five blocks cache in Magento 2, or five approaches to caching, and when and how to use them. Interestingly, this article will cover both full page and block cache. Let’s explore each type of block cache together!

In case, cache_lifetime of the block is set to a number greater than 0, the block is cacheable

to cache any block, you need to override this function