That is strange since both use same old communication system. New version just has some more answers it understands. But for correct analysis I need the written log to see what is happening. From what I see the serial seems to swallow or replace parts with older communication parts. Have seen that happen under high traffic e.g. echo enabled. In a parallel thread a used with same printer said with ping pong enabled the communication works for him also in 2.0.
Also last question - which board does the printer use and which baud rate is set? If I have that board I could try to reproduce.
No one wanting to share the full log part that explains what is going wrong? Com errors are quite normal and normally get fixed by host/server. The communication has not been changed for a while and is known to normally work, so without more information I have no point to start fixing.
From dropbox/google drive share link. You can send it as pm if you think public is not good. Or use a site like pastebin to share the data.
Pleaee make sure it is the written log from host not the log in the gui which is incomplete.
is more clear. Here it seems the M117 command confuses the firmware. I guess it is the same in case 1 also we do not see it but line 37 seems also a M117 command.
So my guess is your firmware can not handle M117 with line number and checksum.
Only solution is in printer settings to deselect "Send ETA to printer display". This disables sending the M117 command coming from host it self. Of course your gcode should also not contain them.
Regular Marlin has no problems with this and it is also correct gcode so it is more a firmware problem as it seems, but with the workaround it should do.
Comments
You see host has send line 17 and firmware I guess send some text I have never seen and then wants line 37.
Second case
is more clear. Here it seems the M117 command confuses the firmware. I guess it is the same in case 1 also we do not see it but line 37 seems also a M117 command.
So my guess is your firmware can not handle M117 with line number and checksum.
Only solution is in printer settings to deselect "Send ETA to printer display". This disables sending the M117 command coming from host it self. Of course your gcode should also not contain them.
Regular Marlin has no problems with this and it is also correct gcode so it is more a firmware problem as it seems, but with the workaround it should do.