If you see this error message then you have tried to run a schematic or a spice netlist in simulation without having added a ground symbol (or a `0` or `GND` ground net in the netlist).
To run a schematic or a spice netlist in simulationit **must** have a ground.
For more, see:
[Tips & Skill > To simulate a schematic, it MUST have a ground]
[Tips & Skill > To simulate a schematic, it MUST have a ground]: https://easyeda.com/bbs_view_1393.htm
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