KiCad ERC: Label not connected to anything

Diagnostic signature

Label not connected to anything

During an Electrical Rules Check (ERC) in the Schematic Editor, KiCad emits this diagnostic when a local, global, or hierarchical label is placed on the schematic but its attachment point is not electrically connected to any wire, pin, or bus.

What it means

In KiCad's schematic capture environment (Eeschema), labels (including local, global, and hierarchical labels) are utilized to establish electrical connectivity across different sections of a schematic or between hierarchical sheets without drawing continuous wires. This ERC warning indicates that the origin point of a placed label (represented by a tiny square attachment point visible when manipulating the label) does not geometrically intersect with a valid electrical primitive, such as a wire segment, a symbol pin, or a bus. As a result, the net assigned to this label remains isolated at this physical location, meaning it will not connect to the intended circuit, which can lead to missing connections or unrouted nets in the subsequent PCB layout.

Why it happens

This diagnostic is primarily caused by minor geometric placement inaccuracies. A user might visually align a label next to a wire or symbol pin but fail to snap the label's exact attachment point onto the schematic grid where the wire or pin terminates. It can also occur if a connecting wire segment was inadvertently deleted, or if a component was dragged or moved without maintaining the attached label. Additionally, if a user places a net label intended purely as a graphical note or textual comment—instead of using the standard plain 'Text' tool—the ERC will flag the label as an orphaned electrical element.

Minimal reproduction

(kicad_sch (version 20231120) (generator eeschema)
  (paper "A4")
  (symbol (lib_id "Device:R") (at 100 100 0) (unit 1))
  (label "SIG_OUT" (at 102 98 0)) ;; Attachment point deliberately missing the pin
)

How to fix it

Adjust the label's position so its attachment point snaps directly onto a valid wire or pin, or replace it with a plain text item if it was intended as a visual comment.

```KiCad Schematic (S-Expression)
(kicad_sch (version 20231120) (generator eeschema)
  (paper "A4")
  (symbol (lib_id "Device:R") (at 100 100 0) (unit 1))
  (label "SIG_OUT" (at 100 96.19 0)) ;; Coordinates precisely matching the component pin
)
```

Step 1

• Locate the unconnected label in the schematic by clicking on the violation marker in the ERC dialog.

Step 2

• Select the offending label and invoke the Move (M) command.

Step 3

• Drag the label until its small rectangular attachment point snaps precisely onto the end of the intended wire, bus, or symbol pin.

Step 4

• If a connecting wire is missing entirely, use the 'Add a wire' (W) tool to draw a line from the circuit to the label's attachment point.

Step 5

• If the label was placed strictly as a visual note rather than a net connection, delete the label and recreate the text using the 'Add a text item' (T) tool.

Step 6

• Re-run the Electrical Rules Checker to verify that the warning has been resolved.

Upstream references

Schematic Editor | 8.0 | English | Documentation - KiCad Docs

eeschema/erc_item.cpp - KiCad Source Code

ERC "Label not connected to anything" in basic bus usage (#12814) · Issue