M112 error when sending gcode from Octoprint to MK3.5S but prints fine from USB stick  

M112 error when sending gcode from Octoprint to MK3.5S but prints fine from USB stick

I just did the upgrade from MK3S to MK3.5S and am having a frustrating problem.

Sending from OctoPrint a gcode file created in Prusa Slicer with the stock MK3.5S profile immediately restarts the printer and then throws up an Emergency Stop/M112 error. There is a very brief display of the OctoPrint logo screen on the printer display, so it gets that far. But then the above sequence happens with the printer restarting and then throwing up an orange error screen with the error message "Emergency stop invoked by G-code (M112)". Here is a screen shot.

As you can see, that screen has a QR code and a web link that looked encouraging, until I tried it -- https://prusa.io/28510 -- and I simply got sent to the Prusa3D homepage 🙄 

HOWEVER: The exact same gcode loaded using the USB stick and prints perfectly.

The other strange thing is that sending the same model sliced with an MK3S profile causes no problem when sending it to the printer for printing -- the OctoPrint screen on the printer display comes up and I can print just fine from there.

Everything is at the latest version:

Prusa Slicer = 2.8.1+win64

MK3.5S firmware = 6.1.3+7898

OctoPrint = 1.10.3

OctoPi = Build 2024.05.14.100113 with "webcamd", based on OctoPi 1.0.0, running on Raspberry Pi 3 Model B Rev 1.2

I have no logs other than the above error screen, since I haven't found any clear info on how to log a session like this (maybe someone can advise?).

Has anyone seen this problem and resolved it? 

Thanks.