I was following the steps shown Here to add sample data to my magento site for testing then i got this error stack below:
It was the last part of the installation where i executed this command: php <your Magento install dir>/bin/magento setup:upgrade
Installing data... PHP Fatal error: Uncaught Error: Call to a member function getDataByKey() on null in C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php:191
Stack trace:
#0 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php(171): Magento\SalesSampleData\Model\Order\Converter->getProductAttributes(Array)
#1 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php(76): Magento\SalesSampleData\Model\Order\Converter->convertProductData(Array)
#2 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order.php(101): Magento\SalesSampleData\Model\Order\Converter->convertRow(Array)
#3 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Setup\Installer.php(30): Magento\SalesSampleData\Model\Order->install(Array)
#4 [internal function]: Magento\SalesSampleData\Setup\Installer->install()
#5 C:\xampp\htdocs\Magento\vendor\magento\framework\App\State in C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php on line 191
Fatal error: Uncaught Error: Call to a member function getDataByKey() on null in C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php:191
Stack trace:
#0 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php(171): Magento\SalesSampleData\Model\Order\Converter->getProductAttributes(Array)
#1 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php(76): Magento\SalesSampleData\Model\Order\Converter->convertProductData(Array)
#2 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order.php(101): Magento\SalesSampleData\Model\Order\Converter->convertRow(Array)
#3 C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Setup\Installer.php(30): Magento\SalesSampleData\Model\Order->install(Array)
#4 [internal function]: Magento\SalesSampleData\Setup\Installer->install()
#5 C:\xampp\htdocs\Magento\vendor\magento\framework\App\State in C:\xampp\htdocs\Magento\magento2-sample-data\app\code\Magento\SalesSampleData\Model\Order\Converter.php on line 191