I just paid for and downloaded WP Smush PRO. I had been using the free version. There were no instructions on how to install the PRO version. Do I deleted the free version? Which file do I actually upload (the download is a folder with more folders and many files). No idea. So I tried installing the PRO version with the file wp-smush.php and got this error: The package could not be installed. PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature I then deleted the free version and tried again. Same error.