What we tested
| File | Bambu Studio said | Actual problem | Result |
|---|---|---|---|
| 40 × 20 mm plane, 2 triangles | Loading of a model file failed. | Open sheet, height 0; file shorter than the reader's 128-byte test | Not loaded (PrusaSlicer 2.9.6 the same) |
| Same plane, 32 triangles | Info: 16 open edges | Open sheet, height 0 | Loaded; nothing to slice |
| 40 × 20 × 0.2 mm plate, 12 triangles | No warning | Closed solid | Loaded and sliced as one layer |
What is going on
Bambu Studio and PrusaSlicer use the same STL reader. It reads 128 bytes after the 84-byte header to decide whether the file is binary or text (source). A binary STL with two triangles is 184 bytes long, too short for that test, so loading fails. The reader also treats a binary file as text when none of those 128 bytes is above 127, which can happen when an exporter writes zero normals.
Other damaged or unsupported files can end in the same message; we only tested these causes. FixSTL read the two-triangle file and reported an open sheet of height 0.
What was actually wrong
How to fix it
- Check the file in FixSTL: the triangle count and height tell you whether it is a sheet.
- Give the surface thickness in your modelling program; in Blender, a Solidify modifier.
- Export the STL again and re-import it.
- If the file is large and still fails, open it in another program and export a fresh binary STL.
Source: Seen in our tests · Bambu Studio 02.08.02.61 on macOS