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https://cart.jlcpcb.com/quote?fromDemo=yes&_ga=2.82280597.2048935692.1626657681-950652181.1601262138
https://support.jlcpcb.com/article/42-how-to-export-altium-pcb-to-gerber-files
Make sure to import the JLCPCB design rules from the link above. below ↓
Run a DRC and correct any errors. Also make sure that your board has a board outline on the Keepout Layer.
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