If you are receiving this error “The package could not be installed. The theme is missing the style.css stylesheet.” while trying to install/update the theme, that means you are doing something not right.
Most probably you are trying to upload the full archive downloaded from Envato Market.
- Instead, you should be looking inside this archive, and select the zip theme folder. This one you should be uploading.
- Or just download only the theme installer zip file and use this file instead. Please check the screenshot below for better understanding: