Hello,
Please try the solution from this topic – https://www.8theme.com/topic/the-package-could-not-be-installed-pclzip_err_bad_format-10-unable-to-find-2/#post-273465 or do the update via FTP – https://xstore.helpscoutdocs.com/article/63-theme-update http://xstore.helpscoutdocs.com/article/37-plugins-update
Regards
