Not sure where to report this, but the library footprints for Molex KK connectors have pads that are too close together. That class of connector has a 250V voltage rating, and the pads have only 1 mil separation. Compare footprint PINHEAD1-6 with KK Molex footprints. Same pin spacing, same size pins, but PINHEAD-6 has about 2.3 mils of clearance, while the Molex footprints have only 1 mil. The design rule checker caught this.
There’s no obvious reason for such tight spacing. That looks like a bad footprint design.
IPC2221B standard trace spacing vs. voltage: http://www.smps.us/pcbtracespacing.html
That link shows a spacing of about 1.25mm for 250V.
The KK footprint hole to hole is ~1.3mm, so it will never meet that
To achieve 250V, a pin would have to be omitted
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1.3mm Hole is a bit big to be honest.
It should be 1.19 +/-0.05mm according to its datasheet.
@John-Nagle: the best way to correct footprints is to change them and create a pull request.
Another way would be to create an issue. (But the preferred way is a pull request.)
Github link: https://github.com/KiCad/Connectors_Molex.pretty
The Molex KK connectors are created with the help of a python script.
https://github.com/pointhi/kicad-footprint-generator
You can change the pad size in this script. Run it.
Copy the resulting footprints to a fork of the Connectors_Molex.pretty repo. (on a branch with a meaningful name)
Create a pull request.
If all goes well you made your first contribution to KiCAD.
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Over sized holes cause dry joint problems on connectors. Still, using the correct hole only gains another 0.1mm, so still two adjacent pins will not survive 250V
It’s still worth correcting it to get an adequate gap for up to 48V