If you want to restore canceled order, rollback order cancellation and undo order cancel action in Magento and Magento 2 use the following SQL query. Order will be restored to “Pending” status.

SET @ORDERID = "41970";
UPDATE `sales_order`
SET `state` = 'new',
`status` = 'pending',
`base_discount_canceled` = '0',
`base_shipping_canceled` = '0',
`base_subtotal_canceled` = '0',
`base_tax_canceled` = '0',
`base_total_canceled` = '0',
`discount_canceled` = '0',
`shipping_canceled` = '0',
`subtotal_canceled` = '0',
`tax_canceled` = '0',
`total_canceled` = '0'
WHERE `entity_id` = @ORDERID;
UPDATE `sales_order_item`
SET `qty_canceled` = '0',
`tax_canceled` = '0',
`discount_tax_compensation_canceled` = '0'
WHERE (`order_id` = @ORDERID)
;

To find a file by name in Linux (Ubuntu, Centos) or macOS in command line use the following command

find /home/username/ -name "*.inc"

SELECT `p`.`sku` FROM `catalog_product_entity` AS `p`
LEFT JOIN `catalog_product_entity_varchar` AS `attr_images`
	ON `attr_images`.`entity_id` = `p`.`entity_id`
	AND `attr_images`.`attribute_id` IN (SELECT `attribute_id` FROM `eav_attribute`
			WHERE `attribute_code` IN ('image', 'small_image', 'thumbnail') AND `entity_type_id` = 4
		)
LEFT JOIN `catalog_product_entity_media_gallery` AS `gallery`
	ON `gallery`.`entity_id` = `p`.`entity_id`

WHERE (`attr_images`.`value` IS NULL OR `attr_images`.`value` = 'no_selection') AND (`gallery`.`value` IS NULL);

grep -Ril "text-to-find-here" /

redis-cli -h <host> -p <port> flushall

The command will remove all data from client connected (with host and port).

You can easily generate self-signed SSL certificate for your local machine using openssl this command line tool

openssl req -x509 -nodes -days 365 -newkey rsa:1024 \
    -keyout /etc/ssl/private/mylocal.key \
    -out /etc/ssl/certs/mylocal.crt

Now you can change your nginx config to use these certificates. Add the following section

server {
    listen               443 ssl;
    ssl_certificate      /etc/ssl/certs/mylocal.crt;
    ssl_certificate_key  /etc/ssl/private/mylocal.key;
    server_name mylocal.local *.mylocal.local;
    set $MAGE_ROOT /projects/mylocal;
    include /projects/mylocal/nginx.conf.sample;
}

SELECT TRX_ID, TRX_REQUESTED_LOCK_ID, TRX_MYSQL_THREAD_ID, TRX_QUERY
FROM INNODB_TRX
WHERE TRX_STATE = 'LOCK WAIT';

SELECT
  waiting_trx_id,
  waiting_pid,
  waiting_query,
  blocking_trx_id,
  blocking_pid,
  blocking_query
FROM sys.innodb_lock_waits;

SELECT
  r.trx_id waiting_trx_id,
  r.trx_mysql_thread_id waiting_thread,
  r.trx_query waiting_query,
  b.trx_id blocking_trx_id,
  b.trx_mysql_thread_id blocking_thread,
  b.trx_query blocking_query
FROM       information_schema.innodb_lock_waits w
INNER JOIN information_schema.innodb_trx b
  ON b.trx_id = w.blocking_trx_id
INNER JOIN information_schema.innodb_trx r
  ON r.trx_id = w.requesting_trx_id;

log stream --predicate  '(process == "smtpd") || (process == "smtp")' --info

$obj = \Magento\Framework\App\ObjectManager::getInstance();
$fileHandler = $obj->create(\Magento\Framework\Logger\Handler\Base::class, ['fileName' => 'var/log/debug.log']);
$logger = $obj->create(\Monolog\Logger::class, [
                'name' => 'save',
                'handlers' => ['file' => $fileHandler],
                'processors' => ['process_id' => $obj->get(\Monolog\Processor\ProcessIdProcessor::class)]
            ]);
$logger->info(var_export(\Magento\Framework\Debug::backtrace(1, 0, 1), 1));

Result could be found in var/log/debug.log

The following solutions helps to find duplicate image file for each product and to remove it.
Create file delete.php in Magento base directory, put the following code into the file.

<?php
include('app/Mage.php');
Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
error_reporting(E_ALL | E_STRICT);
ini_set('display_errors', 1);
ob_implicit_flush(1);

$mediaApi  = Mage::getModel("catalog/product_attribute_media_api");
$_products = Mage::getModel('catalog/product')->getCollection();
$i         = 0;
$total     = count($_products);
$count     = 0;
foreach ($_products as $_prod) {
    $_product   = Mage::getModel('catalog/product')->load($_prod->getId());
    $_md5Values = array();

    //protected base image
    $baseImage = $_product->getImage();
    if ($baseImage != 'no_selection') {
        $filePath = Mage::getBaseDir('media') . '/catalog/product' . $baseImage;
        if (file_exists($filePath)) {
            $_md5Values[] = md5(file_get_contents($filePath));
        }
    }

    $i++;
    echo "processing product $i of $total " . PHP_EOL;

    // Loop through product images
    $_images = $_product->getMediaGalleryImages();
    if ($_images) {
        foreach ($_images as $_image) {
            //protected base image
            if ($_image->getFile() == $baseImage) {
                continue;
            }

            $filePath = Mage::getBaseDir('media') . '/catalog/product' . $_image->getFile();
            if (!file_exists($filePath)) {
                continue;
            }
            $md5 = md5(file_get_contents($filePath));
            if (in_array($md5, $_md5Values)) {
                $mediaApi->remove($_product->getId(), $_image->getFile());
                echo 'removed duplicate image from ' . $_product->getSku() . PHP_EOL;
                $count++;
            } else {
                $_md5Values[] = $md5;
            }
        }
    }
}

To launch the script just launch in terminal

>php delete.php

Or visit

http://YourWebsiteURL/delete.php

from your browser.

Thanks to Aadil for a solution.