Note that as of WP v5.5 this plugins functionality is included in WP Core and this plugin is not required anymore. If you are running WP v5.5 or greater, you can de-activate and delete/remove this plugin. This plugin will still continue work fine with versions of WordPress less than v5.5. WordPress will let you install a NEW plugin or theme from a zip file, but it does NOT allow you to upgrade them from a zip file. If you try to upgrade from a zip file, you will get an error message that says “destination already exists” and the upgrade will fail. WordPress will not allow you to upgrade from a zip file. Update Theme and Plugins from Zip File will allow you to easily upgrade from a zip file, avoiding the “destination already exists” error message. There is also an option to create a backup copy of the old plugin or theme, in case there is a problem with the new version.