KiCad "Pin not connected" ERC error and the no-connect flag
KiCad electrical rule check (schematic) message: Pin not connected (pin_not_connected in kicad-cli reports).
What it means
A symbol pin has no wire, label or other pin on it, and is not marked as intentionally unused. Either connect it, or place a no-connect flag (the X, shortcut Q) on pins you mean to leave open.
Common causes
- Pins left open on purpose without a no-connect flag.
- A wire that ends near the pin but not on it, often from off-grid placement.
- A missed connection.
How to fix it
- Place a no-connect flag on pins that should stay open.
- Drag the wire end onto the pin with snapping on.
- Check the datasheet: some "NC" pins must be tied off, and some unused inputs must not float.
Find every “Pin not connected” on your board
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Check my KiCad projectRelated KiCad ERC checks
- Symbol pin or wire end off connection grid
- Wires not connected to anything
- A pin with a "no connection" flag is connected (
no_connect_connected)
Checked against KiCad 10's source and documentation. Last reviewed 2026-11-07.
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