Files open with missing geometry

The only geometry, breps, in the files are missing when
MissingBrepWithFile-Open-190502.3dm (31.8 KB)
MissingBrepsWithFile-Open-190516.3dm (47.8 KB)
are _Opened in V6, but they appear with _Import. They also appear when _Opened in the WIP. The files were made with an older V6, circa May 2019.

Hi Steve - I see that… I do not have any explanation - the object table is indeed empty when the file is opened in v6. were the objects made in any special way , that is other than with standard Rhino commands?


They were exported from V6 of STEP file imports. The breps are a subset of other breps. I tracked down what I believe is the V6 file with the one of the larger breps, and it opens with the problem faces intact.

Hi Steve, so the process was:
Import step file to Rhino.
Select some faces and export these to 3dm format.



  1. _Import the STEP file with Join surfaces unchecked. These breps still import with 2 faces each due to how Rhino handles seamless surfaces from STEP files.
  2. _Export to a 3dm file, possibly while in the _BlockEdit state.

Hey Steve,

We fixed a bug recently that sounds an awful lot like what you’re experiencing, especially with regard to your last comments. It would be good to know if BlockEdit was indeed involved. This is the bug fix I’m referring to.


I’m 99% confident that my samples were exported while in the _BlockEdit state.

The bug does look similar, except when the files are _Opened in V6, the block definitions are also missing. When I export data from the _BlockEdit state, I usually open the new file shortly after and would quickly realize that geometry was missing. In the case of my two files, they were samples I had saved about 11 months ago to debug one of my scripts and don’t know whether the version of V6 I was using then could open them correctly. This is first time I’ve seen something like this.