According to [https://guideusermanual.com/product-name-d80-manual&po=4315&lang=English|Nikon D80 Manual] if you see "ERR" on your LCD or electronic viewfinder, you likely have experienced one of three problems. First, the shutter button may not have depressed properly. Second, the camera could not capture the image using your manual exposure settings; try changing the settings or using automatic settings. Third, the Nikon camera may have experienced a start-up error. Remove the battery and memory card for at least 15 minutes and try turning on the camera again.