Updating template to latest version fails

When I try to update NTS Kay 6 using the Install new template button I get a failure message: Joomla\Filesystem\File::move: Rename failed.

Hi BasilC,
Please download the template latest version on our website and update to your website.

Kind regards,

I was using the latest update already. Have tried again with same result. And I see that another user has encountered exactly the same issue, which is also being discussed on the Kunena forums.

I activated debugging, but nothing shows up.

Hi BasilC,
Please try to follow some below steps:
1. Change the Aurelia template to the default template.
2. Uninstall the NTS Kay template.
3. Click to "New Template" button and re-install the NTS Kay template.

***Note: Remember to back up your configuration in case you have changed it from the default configuration.

Regards,