DRC shows unconnected pin

Just laid out a small PCB, and when I run a DRC, I get a load of expected “Courtyards too close”, which I know isn’t a real issue. However, I’m also getting an error about an unconnected item… telling me that “Pad 2 of C20 on all copper layers isn’t connected to the Zone Outline (GNDA) on B.CU”

Which is odd, because when I look, I can clearly see that it IS connected ok, unless I’m missing something stupid!

All the files are in a dropbox folder, if anyone wants to take a look:

(shout if you need any other files)

If you do not care about the couryard warnings, you can get rid of it with:
Pcbnew / File / Board Setup / Design Rules / [ ] Prohibit overlapping courtyards

The piece of copper in the screenshot below is not connected to the rest:

Euhm, Oops.
The screenshot above is not exactly right because the pad is connected on the other side of the board.
However you have quite a lot of copper areas that have very minimal connections to other copper areas and this is far from optimal.

If KiCad finds that not all of the pads in a net are connected. It picks a random pin to place the DRC error on, and because of the labyrinth of your zones this will require some searching, or just general improvements of the zone, to make a single continuous GND zone on one layer and put (most of) the tracks on the other side.

It looks like your immediate problem is with U4 pin 5. It’s connected to a small piece of copper on both the top and bottom sides that seem to go nowhere.

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I can see that, on the “red” layer it is indeed ‘isolated’, but (ignoring any AC performance issues) it IS connected in two places to 0v, via two GNDA pins that connect through to the 0v on the other side. I guess it’s ‘just the way Kicad’s DRC works’

Now that I’m happy with the design (seem silly to do it sooner), I’ve added a load of vias, to link the two GND planes, so the AC performance should be absolutely fine. And KiCad now seems to have stop complaining about the bit of isolated copper!

Thanks for the pointer to turning off the courtyard warning! Yet another setup menu to think about!!!