Pin connected to other pins, but not driven by any other pin

[Dave_Thomas]

FINALLY FOUND IT!

Just like you said–a tiny GND label in a subsheet. Left over from before I decided to have a separate ground for power and small signals.

Thanks for the help! Glad I bothered to track it down–it was a real issue.

[roboya]

Hello!

If I may add my own explanation for something which I now think it’s obvious… but took me ages to understand… (not proud of it). I will add a recent example.
Basically Kicad expects your circuit to have some power at some point in the circuit. We can’t blame the software on that point.
Usually I design boards with an input power connector. As for the connector type on the schematic, it might be a row of pins, for instance 01x05 for the symbol. These generic symbols are usually “passive”, so when Kicad checks ERC, it finds out that the circuit has no power at all, although the connector used is actually a power connector. For example a circuit using a power connector like this will generate 5 errors, one per power net.

Now the only way to prevent to have errors is to tell Kicad, this is a power net. And if you add a power flag for each of the power lines, then you will have no more errors. I think it’s more logical to set this flag on the power connector itself, that’s why I group them all here.

What is difficult to understand at first, ist that although you have many similar nets, you will have an error on only one of them, and the position of this error is random. Probably the first in the parsing order of the ERC tool. You can see on the next image than the top +5V has no ERC issue while the bottom rght one has.

I’m aware that this is a little out of the original poster question, but I would be pleased if it can save some time to newcomers.

Pascal