$this->addColumn('barcode', ['header' => __('Barcode'), 'index' => 'barcode']);

rm -rf var/page_cache/*
rm -rf var/cache/*
rm -rf generated/*
rm -rf var/view_preprocessed/*
rm -rf pub/static/*

php  bin/magento  setup:upgrade;
php  bin/magento setup:di:compile;
php  bin/magento setup:static-content:deploy -f;