Default Property warning at startup

When I start up my project at 45% I get this error:

Default Property warnings and errors:
Error: CDO Constructor (ThumbnailManager): Failed to find
/Engine/MapTemplates/Sky/DaylightAmbientCubemap

Before the error I was deleting some of the default stuff to make my build smaller. The level loads and works fine but I would like to get rid of this error as I would assume there will be problems when I build it. Also I restored an old version with all the starter content in it again and am still getting this error. I trook the ambientcubemap from some other saved game and put it in this one and still got the error. I deleted all the content in my saved folder…that really messed things up. I restored it…still getting the error. Any ideas?
Thanks!

Fixed this by right clicking on 4.8.3 version in game launcher and doing “verify.” Thanks.

what game launcher? I am getting this in android after removing engine content. Although game works fine. But I can’t release it like this.