GRBL Error Codes
Expected Command Letter
G-code words consist of a letter and a value. Letter was not found.
Bad Number Format
Missing the expected G-code word value or numeric value format is not valid
Grbl ‘$’ system command was not recognized or supported.
Value < 0
Negative value received for an expected positive value.
Homing cycle failure. Homing is not enabled via settings.
EEPROM Read Fail
An EEPROM read failed. Auto-restoring affected EEPROM to default values.
Grbl ‘$’ command cannot be used unless Grbl is IDLE. Ensures smooth operation during a job.
G-code commands are locked out during alarm or jog state.
Homing Not Enabled
Soft limits cannot be enabled without homing also enabled.
Max characters per line exceeded. File most likely formatted improperly
Line Length Exceeded
Build info or startup line exceeded EEPROM line length limit. Line not stored.
Jog target exceeds machine travel. Jog command has been ignored.
Laser mode requires PWM output.
Unsupported or invalid g-code command found in block. This usually means that you used the wrong Post-Processor to make your file, or that some incompatible code within needs to be manually deleted.
Modal Group Violation
More than one g-code command from same modal group found in block.
Undefined Feed Rate
Feed rate has not yet been set or is undefined.
Error codes 23-38 all give different reasons for a file failing. To look up further, google "GRBL Error Code [Insert Number] for more information.