Invalid reply from server endpoint when activating the theme

Hello,

I bought your theme a few hours ago and try to use the template cloud after using it on the site. But as I came across in google, after activating the theme, the template page gives the following error “Invalid reply from server endpoint” Without the activation key, the page works normally. But requires activation. Content is visible and gives no errors.

I see this happens more often. I have reset the activation 5 times and the result remains the same. Without activation the template page remains accessible, with activation I get the error. So no template page. What can be done about this?

Regards

thanks anyway, found the problem caused by a plugin.