KiCad DRC Warning: Track has unconnected end

Diagnostic signature

Track has unconnected end

A Design Rule Check (DRC) warning indicating that a routed copper track segment does not terminate at a valid electrical node, such as a pad, via, or another contiguous track.

What it means

In KiCad's PCB Editor (Pcbnew), this diagnostic signifies that the topological end of a routed copper track is floating. From the perspective of the Design Rule Checker, every trace must form a valid electrical connection by terminating at another recognized copper object belonging to the same net, such as a footprint pad, a via, a copper zone, or a contiguous track segment. When a trace ends in empty space without anchoring to one of these valid endpoints, the layout engine identifies it as an incomplete connection, commonly referred to as a dangling track, a stub, or an unintended antenna.

Why it happens

This warning is triggered when the layout editor detects a track coordinate that does not geometrically intersect with a valid terminal node. Common triggers include manually routing a trace and stopping before reaching the destination pad, deleting a component footprint while inadvertently leaving its previously attached traces behind on the board, or dragging footprints, which can sometimes sever existing track connections. It frequently occurs due to microscopic alignment issues where a track visually overlaps a pad but misses the exact snap point or attachment center defined by the grid, leaving a minute gap that the DRC algorithm strictly flags as unconnected.

Minimal reproduction

(kicad_pcb (version 20240108) (generator pcbnew)
  (net 1 "Net-(J1-Pad1)")
  (footprint "Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical" (at 100 100)
    (pad 1 thru_hole rect (at 0 0) (size 1.7 1.7) (drill 1) (layers *.Cu *.Mask) (net 1))
  )
  (segment (start 100 100) (end 110 100) (width 0.25) (layer "F.Cu") (net 1))
)

How to fix it

Remove or complete the dangling track segments either manually by selecting them from the DRC dialog, or automatically using Pcbnew's built-in cleanup utilities.

```kicad-pcb
(kicad_pcb (version 20240108) (generator pcbnew)
  (net 1 "Net-(J1-Pad1)")
  (footprint "Connector_PinHeader_2.54mm:PinHeader_1x01_P2.54mm_Vertical" (at 100 100)
    (pad 1 thru_hole rect (at 0 0) (size 1.7 1.7) (drill 1) (layers *.Cu *.Mask) (net 1))
  )
)
```

Step 1

• To resolve the issue manually, select the specific warning in the DRC Control dialog to immediately highlight the offending dangling track segment on the canvas.

Step 2

• If the highlighted segment is an unwanted stub, press the Delete key to remove it. If it is an incomplete route, press 'X' to continue routing it to its intended destination.

Step 3

• To resolve the issue globally across the entire board, navigate to the 'Edit' menu and select 'Cleanup Tracks & Vias...'.

Step 4

• Check the box for 'Delete dangling tracks' and click 'OK' to automatically purge all unconnected track segments from the layout.

Upstream references

KiCad 8.0 PCB Editor Documentation - Design Rule Checking

Issue #14211: Track has unconnected end warning for track stubs inside vias/pads

Issue #12348: Silence 'track has unconnected end' DRC errors for tracks fully encompassed by pads