Error when trying to export step

KiCad tells me " * error reading file: “c:\blablabla\mypcb.kicad_pcb” and " * SEXPR is not a symbol type!" when trying to export a step file.
Never had any troubles exporting step in other projects before and I have no idea what this SEXPR is, so… any help anybody?
EDIT: Export as VRML or somthing else seems to work, but I do need the step file…
Obviously there seems to be something invalid in the kicad_pcb file, any idea what to look for ?
Many thanks in advance!

Can you post the pcb file here?

Unfortunately I’m not allowed to upload in this forum yet, because I’m a new user

@Joan_Sparky can you help out with the posting permissions?

@Platinierer Can you copy and paste the full error message?

@Platinierer can even do it them selfes. To get to the trust level required to add attachemnts they need to:

Get to trust level 1 by…

  • Entering at least 5 topics
  • Reading at least 30 posts
  • Spend a total of 10 minutes reading posts


An alternative is to upload the project to any file sharing site and add a link here. (new users area allowed two links per post)


I have just promoted @Platinierer to level 1 basic User, so you can attach.
Behave yourself.

1 Like

Thanks for all your help guys, I’ve put the file on my server:

The output messages are:
Executing ‘“C:\Program Files\KiCad\bin\kicad2step.exe” --no-virtual --drill-origin -f -o “E:\DoesNotStep.step” “E:\DoesNotStep.kicad_pcb”’
Warning: 12:32:36: * error reading file: ‘E:\DoesNotStep.kicad_pcb’
Warning: * SEXPR is not a symbol type!
Info: STEP file has been created successfully.

And in contrast to the text, Kicad does not create a step file

I can confirm this with

Version: (6.0.0-rc1-dev-1400-g95dcc30ff), release build
Platform: Windows 7 (build 7601, Service Pack 1), 64-bit edition, 64 bit, Little endian, wxMSW

You can try FreeCAD+StepUp. StepUp can load a board file and make a 3D model out of it, then export it to STEP.

SEXPR doesn’t refer to anything controversial or xxx rated, it means s-expression syntax which KiCad uses for pcb files, it’s a bit similar to lisp programming language syntax if you happen to know it. If the file was completely created by KiCad, no hand editing or scripting, there must be a bug somewhere in KiCad.

Thanks for your research.
Yes, the file was created only using KiCad, no editing or scripting involved. But I did import some other, only KiCad created .kicad_pcb files in the creating process to recycle some older work.

no issues with StepUp & FreeCAD

1 Like

Again, many thanks everybody! I will use FreeCad+StepUp as a workaround to create the enclosure.

But I’m still very interested to fix the error in the .kicad_pcb file. Is there any tool to check the syntax of these files?

1 Like

I believe if KiCad (and StepUp) can read the file and it works fine there’s no syntax error there. The KiCad’s internal STEP exporter may be buggy. KiCad’s files are human readable, you can easily read and understand it, but your file is pretty long to inspect manually. We would benefit from better error message (line and column numbers) by the KiCad STEP exporter.

1 Like

@Seth_h, is 214d8d3703b3 meant to fix this?


Should work in future nightlies

i just tried to export the PCB with the latest development version 6.0.0-rc1-dev-1423-g6eca92436, and it works perfectly. Well done! Many thanks and Happy Holidays everybody!

1 Like

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.