Hi KV90, welcome to the forum.
First thing to do in such a case is to make the sketch visible and use the "Validate sketch" tool in Sketcher (or PartDesign). And here we go finding two missing coincidences!
If you fix them - either automatically in the tool or manually - still reports a much more severe problem in report view. BTW: this error was there before fixing the coincidences.
App::Document::recompute(): cyclic dependency detected
Next step in the investigation is the Std DependencyGraph
, which shows This should never have happened. So we are very much interested how you got there!
To fix it make the Origin in the body visible, select XY plane and attach the sketch to it (icon: blue cube with a sketch at the side). Either leave the attachment mode as is or use "Flat face(recommended)".
The sketch still shows the error, but a recompute fixes it.
Using black color for solids is not advised before your model is finished, because the black color is used as an indicator for invalid solids.