How to I resolve the issue of error code 20?

A couple of things to check on - make sure your device type is set to the correct type: GRBL.

-Click “Devices” in the ‘Laser’ window
-Double click your laser in the list
-Change the selected device to ‘GRBL’ if it is not already
-click next until you’re done

Then, in your Device Settings (‘Edit’ > ‘Device Settings’), make sure you do not have ‘GCode Clustering’ enabled.

If neither of those things help, please save and send us the GCode from an example project file you’re seeing this issue with (‘File’ > ‘Save GCode’) - you’ll need to change the file extension to .txt to post it here.