saeme happening to me,[0;31m[2018-05-29 11:28:36][ERROR]: Class Magento\Catalog\Block\Adminhtml\Product\Helper\Form\BaseImag‌​e does not exist but mentioned in: catalog_eav_attribute.frontend_input_renderer for attribute_id=106[0m

i am getting the same problem in magento 2.1.8

thanks for your reply , we are planning to select available countries by data entry. so i am wondering how to add a new attribute with all countries list simillar to country of manufacture