GRBL found Gcode error?

Hello All,
I am exporting Gcode from Desk Proto and using en edited Shapeoko 3 machine profile as they do not have X-Carve listed. I am then attempting to send the G code with Pic Sender. I keep getting “GRBL has found g code error in line 4 or before line 4”. I have no idea what this is. I changed my GRBL settings to allow max z speed of 600mm just in case this was the problem. I also changed a plunge rate setting in Desk Proto to not allow the plunge to be 100% of feed rate, I am only allowing 50% of feed rate.
Could someone tell me what the error may be? I have tried editing the Feed rate in line 4 but this does not help.
The first few lines of Gcode is below.

G00 X133.905 Y43.798 Z3.640
G01 Z0.640 F1150 S16000
G01 Y41.618 F575
G01 X132.451 Y38.711
G01 X132.088 Y38.348
G01 X131.361 Y36.895
G01 Y35.078
G01 X132.451 Y34.715
G01 X132.815
G01 X134.268 Y35.078
G01 X135.721 Y35.805
G01 X138.265 Y38.348
G01 X138.991 Y39.801
G01 X139.355 Y41.981
G01 Y43.435
G01 X138.991 Y45.251
G01 X137.901 Y47.431

Remove the “%” line at the beginning of the G-code.

Hi LarryM,
Thanks for the response. Amy idea why that would be in the code?

It’s most likely put there by the post processor that you used to generate the G-code.