Probable DRC bug in PCBnew - part 1

I’m seeing what I think is a bug in the DRC. I’m getting


In reality this track is 4 mm away from the polygon it claims is too close, but I notice that there is a kind of ‘ghost’ polygon (the dots in the image in Part 2 of this post) which I can make appear by right clicking on the error message and choosing to view the polygon. Anyone have any ideas?

Please don’t create several topics for one question. It’s very confusing.

Can you give us the board file, not just a screenshot?

zl3ix is a new KiCadder, and has not yet accumulated the mandatory 1/2 hour before files can be uploaded.

I needed to upload 2 files, and it wouldn’t let me do that in a single post. Something about being a new member.

you can make two post here (in the same thread), no need to make two separated threads to post twice.

I guess you have a zone on the B.Cu layer, the green background. Please use the “Do not show filled areas in zones” icon in order you can see what is the polygon.

Could you share the board with us (or PM it to me)?


Sorry, I don’t know the acronym ‘PM’. I would be happy to send files by whatever method is allowed. I don’t think I’m allowed to post them here .

PM = private message on the forum. Or just create a bug report on gitlab and attach the PCB there.

I tried to find a Private Message button, but didn’t find one. How do I do that?

Click on the Users Avatar button, then clicky “Message”.

Can you confirm that you received the PCB file in a private message yesterday, please. It’s the first time I’ve tried to do that, and I’m not sure that it worked. Thanks

Yes, got it. Thanks. I don’t see your error though (and the ghost polygon). Which version of KiCad do you have?

Version 5.1.9-1 release build


As seen from the DRC message the polygon you see is a graphic polygon.

Graphic polygons are used to fill the area on the board with copper to maintain the thickness of the board. This is necessary as the board will need to be clamped for various processes throughout fabrication, and maintaining copper thickness in certain areas of the board ensures even clamping.

To add a graphics polygon:

  1. Select the graphics polygon icon in the vertical toolbar ( the mouse pointer is on the icon in the image )
  2. The polygon properties can be set as given in the image below
  3. To do a DRC go to Inspect and select Design Rules Checker

A month later, with a brand new design I’m seeing exactly the same nonsense. It’s complaining about a via that is nearly 100 mm away from the polygon, while another via 5 mm away is apparently OK.

The polygon in question is part of a printed microwave decoupling stub in the form of a quarter segment of a circle. The segment is made up of enough triangle ellipses joined at the ends with a thick arc to smooth things out. Is there something about that construction that’s illegal?

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