Trying to import demo content into a site to help me design the home page, but the demo content file gives a 500 error. In addition, when I press the back button, WordPress importer says “Sorry, there has been an error.
File is empty. Please upload something more substantial. This error could also be caused by uploads being disabled in your php.ini or by post_max_size being defined as smaller than upload_max_filesize in php.ini.”

How to fix?