What is an open path, and how do I fix “filled shape is open”?
Updated Nov 11, 2026
Short answer: An open path is a line whose ends do not meet. Join the pieces and close the gap so the shape can be cut out or filled.
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What an open path is
A closed shape is a line that ends where it started, like a circle. An open path is a line whose two ends do not meet. To cut a piece out, or to fill a shape for engraving, the outline has to be closed.
Why it happens
- A tiny gap. The last point stops just short of the first. You cannot see a 0.05 mm gap, but the software can.
- An outline in pieces. Files from CAD programs, online converters and some tracing tools save one outline as many separate line pieces. They touch, but they are not joined, so the software sees many open paths instead of one shape.
- A shape that was cut apart while editing and never rejoined.
How to fix it
- Drop the file into the checker above. Every open end is marked with a red dot.
- Press "Fix everything I can". Pieces that touch are joined into one shape, and shapes whose ends nearly meet are closed.
- Read what is left. Lines that stay open are listed. If one should cut out a piece, draw the missing part in your design program.
By hand: in Inkscape, use the Node tool, select the two end points and press "Join selected nodes". In Illustrator, select the path and use Object › Path › Join. In LightBurn, Edit › Select Open Shapes shows them, and Edit › Auto-Join joins pieces that touch.
Real example: before and after
What the checker found
- 8 open shapes
- Size: 125 mm (4.92 in) wide × 61.4 mm (2.42 in) tall
What was fixed
- Joined 6 broken pieces into 1 whole shape.
- Closed 2 shapes whose ends nearly met.
Download: before (SVG) · after (SVG)
Questions
Can a laser cut an open path?
Yes, a laser follows the line whether it is open or closed. But an open outline cannot cut a piece free, cannot be filled for engraving, and some programs refuse it, for example with a "filled shape is open" message.
Why does my outline look closed but the software says it is open?
The gap is too small to see, often a few hundredths of a millimeter, or the outline is many separate pieces that only touch. Zoom right in on corners, or drop the file in the checker, which marks every open end in red.
Will the fix change my design?
Only at the gaps. Pieces whose ends are within 0.5 mm are joined, and shapes whose two ends are within 0.5 mm are closed with a tiny straight line. You can change the 0.5 mm under More settings.
I want an open line, for scoring. Is that a problem?
No. For lasers, the checker tells you which lines stay open so you can confirm they are score or engrave lines.