September 4, 2026
Troubleshooting JLCPCB Gerber Upload and CAM Tool Compatibility Errors
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You exported your Gerbers from KiCad, EasyEDA, or another EDA (electronic design automation) tool, uploaded them to JLCPCB, and hit an error. A JLCPCB Gerber file error usually traces back to a missing outline, a stray file attribute, or a zip packaged in a way JLCPCB's CAM (computer-aided manufacturing) tool doesn't expect. This guide maps the frequent rejection messages to their causes and fixes.
Why does JLCPCB reject my Gerbers? Its CAM tool parses every uploaded file before accepting an order and rejects anything that doesn't match its expected structure. The table below lists the error messages engineers run into most often, next to the cause behind each one.
| Error Message | Most Likely Cause |
|---|---|
| "Cannot be read by CAM tool" | Wrong Gerber format, missing drill file, or a zip packaged incorrectly |
| "Gerber file missing board outline" | Edge.Cuts layer not exported, or exported to the wrong layer |
| "Excellon drill file not found" | Drill file exported separately, or left out of the zip |
| "Multiple outline layers detected" | A courtyard or fabrication layer included as a second outline |
| "File format not recognized" | Gerber X2 attributes the CAM tool can't parse |
Each error traces to a mismatch between what your EDA tool exported and what the CAM tool expects. The sections below cover each cause, starting with the frequent ones.
This JLCPCB Gerber file error rarely comes from a single cause. Work through these checks in order:
The CAM tool needs a clean, closed board outline to define the shape it will route and drill. Without one, it has no reference for where the board edge sits relative to your copper and hole data.
Gerber X2 format extends standard RS-274X with embedded attributes for layer function, aperture use, and net data. Gerber X2 is a genuine improvement for traceability, but JLCPCB's CAM tool doesn't parse every attribute correctly. One unrecognized line often causes the Gerber X2 format errors that PCB designers report.
If your tool doesn't expose an X2 toggle, check the header lines of each Gerber file for %TF attribute statements and strip them, though re-exporting with X2 disabled is more reliable.
Flux's Gerber export defaults are built around what fabrication houses like JLCPCB actually expect, so most of the errors above don't come up when exporting directly from Flux.
Flux's Gerber export documentation covers the full export dialog if you want the complete reference. You can also skip the manual troubleshooting entirely by designing your next board in Flux and exporting Gerbers that JLCPCB's CAM tool accepts on the first try.
A quick check before you upload catches most errors before JLCPCB's CAM tool ever sees the file.
A JLCPCB Gerber file error costs time you don't have before a deadline. Export your next board from Flux instead. Flux’s Gerber defaults already match what JLCPCB's CAM tool expects, with no X2 toggle to remember or outline layer to double-check by hand. Try exporting your board's Gerber files from Flux and run them through JLCPCB's viewer before your next order.
JLCPCB rejects Gerber files most often over a missing or open board outline, extra non-Gerber files in the zip, or Gerber X2 attributes its CAM tool can't parse.
JLCPCB's CAM tool works most reliably with standard RS-274X Gerber and Excellon drill files, not Gerber X2.
Check the zip for extra files, confirm the outline is a closed polygon on its own layer, and re-export without Gerber X2 attributes if your tool defaults to that format.
Yes, JLCPCB requires an Excellon drill file with the Gerbers, or the upload fails with "Excellon drill file not found."
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