It seems that you don’t have Envato Toolkit activated, please install it so that you could be notified automatically of new Daynight updates!
You could download the plugin here
I have deleted, downloaded, installed, re-deleted, re-downloaded, & re-installed BOTH versions of your plugin about a zillion times and that error wont go away! What’s going on??
Have you removed first completely the old version of Envato Toolkit plugin from your WordPress website, as explained in this installation tutorial: https://envato.com/market-plugin/upgrading/ ? If you scroll down that page, you’ll find more info.
You should delete completely the Envato Toolkit plugin first and only then install the new one, Envato Market plugin.
That’s exactly the idea
Delete them both, it’s safer - and install from scratch Envato Market plugin (not Envato Toolkit plugin, don’t install that one anymore)