GCodes: Attempt to read a GCode unsigned array that is too long

[resam]

I just noticed today that I get the following warning/error message on PanelDue console tab after I power-up/reset my DuetWifi:
GCodes: Attempt to read a GCode unsigned array that is too long: M350 X16 Y16 Z16 E16:16 I1

The weird thing is, I'm tracking my config.g with git since day-0 and this config line is unchanged since then. However, I've never seen this warning message before...

I'm running 1.21 for a while now - is this a new message, or what is happening here?
I guess the config line in question is obviously wrong I suppose, since I'm running a CoreXY with dual Z (one on the Z driver, and one on the E1 driver)...

The only recent change was:
M584 X0 Y1 Z2:4 ; Drive mapping: 0=A, 1=B, 2 and 4 are individual Z steppers
got changed to:
M584 X0 Y1 Z2:4 E3 ; Drive mapping: 0=A, 1=B, 2 and 4 are individual Z steppers, 3=Extruder

I'm currently running a print, but once it's done, I will try to fix the M350. Do I need to specify Z microstepping as Z16:16 or does this get applied to both driver automatically?

[Dougal1957]

@resam looks to me that you have a space between the colon and 16 on the E parameter section reckon that is your issue try removing it and no you don't need E16:16 if you dont have a second extruder

[dc42]

It's because you have declared only one extruder in M584 but you have provided two M350 E values.

[resam]

Print completed - so I removed the :16 from M350. Now the error is gone.
Thx!