Try to inherit a Theme but dont get the new Theme to work properly

I am following this Guide: https://learn.getgrav.org/16/themes/customization#inheriting-manually

I am currently using Quark Open Publishing as Theme and would like to use it as Base-Theme.

So my new Theme-YAML looks like this:

streams:
 schemes:
   theme:
     type: ReadOnlyStream
     prefixes:
       '':
         - user/themes/KageCustomTheme
         - user/themes/quark-open-publishing

And if I switch the Theme to my custom Theme I get this error on the Website:

The Logs say exactly the same:

Template "partials/hero.html.twig" is not defined in "blog.html.twig" at line 34.

But I can't really do something with this Error. And Grav should actually just use the old Theme right?

I found only devtools plugin properly creates a child theme. I never managed to make child theme work when creating step by step manually. Also never bothered to see what's the difference between manual and CLI created themes 🤷‍♂️

Good Point, but I tried it on my Server (IONOS) and doesn't seem to work.

Will now use a Backup locally (Windows) to create it... Hopefully this works.

Nope, didn't work at all. Still the same error as in the Screenshot attached in the Start-Post.

Can any Theme be inherited?

This!

pffttt

Now I need to switch everything over to my newly created theme. Thanks!

Buuuttt, do I need to make sure that the Partials in my Theme get Updated when the Parent-Theme gets updated.

Or is there some Mechanism already in Place in Grav?

@Snickbrack:
Or is there some Mechanism already in Place in Grav?

Not sure, but I don't think so. When theme updates, I believe you'd need to check if any of your overwritten files were affected

Okay thanks. Fine for me. I have the Feeling that for my Theme there wont be any Updates soon.