Error message while trying to export in .stl format

[Alohaa]

Hi,
Sometimes I get an error message when I want to export an object in the .stl format (my Sketchup is in German; I translated the message's text with deepl.com

"Internal error
Unexpected error occurred; the operation cannot be completed. This can be fixed, if necessary, by checking the model for problems and correcting them."

There are 2 options to choose from: "Fix problems" and "Cancel".
When I press the button "Fix Problems", each time the error occurs a new window appears with the heading "Validity Check" and the text "Results of Validity Check - No Problems Found".

It just arrived when I tried to export the object in the attached image.

What should I do?
Sincerely
Alohaa

P.S.: by the way, sometimes a file is saved in 2 formats, the Sketchup format skp and also as skb. What is this 2nd format for?

---

---

Pyramidendach.skp

[Dave R]

Are you selecting only those components shown in your screen shot for export? And do you have the box for Export only current selection checked?

The .skb file is a back up copy of the .skp file. Most of the time you shouldn't need it but it can be useful if something in the .skp file becomes corrupted.

By the way, are you planning to 3D print everything in your model? Currently only the white frames at the left would be printable. The parts shown in blue have their back faces exposed. The blue back faces point toward the print media and the white front faces to air. Those components don't report as solid, either. That means they aren't printable.

[Alohaa]

"Are you selecting only those components shown in your screen shot for export? And do you have the box for Export only current selection checked?"

Yes to both.

"are you planning to 3D print everything in your model?"
No, I mill it