Printer errors: 251 and 201

Hello,

I am using a printer that has a Melzi 2.0 board with Marlin an d found issues when trying to print. The printer prints the file, but while printing this is what goes on the log:

21:37 16.05.2019] Starting job on "STARTT" - "Marlin" with design "YBeltTensionerBlock_2883151_2883223.gcode"
[21:37 16.05.2019] Printer status changed: from idle to downloading
[21:37 16.05.2019] 3DPrinterOS Streaming started
[21:37 16.05.2019] Software version: 6.1.0
[21:37 16.05.2019] Printing now...
[21:37 16.05.2019] Printer status changed: from downloading to heating
[21:38 16.05.2019] Printer error: 251 : Warning! Timeout while waiting for ok. Assuming printer's firmware malfunction.
[21:38 16.05.2019] Printer status changed: from heating to connecting
[21:38 16.05.2019] Printer status changed: from connecting to heating
[21:38 16.05.2019] Printer status changed: from heating to printing
[21:38 16.05.2019] Printer error: 201 : Error:Missing linenumber

[21:38 16.05.2019] Printer status changed: from printing to connecting
[21:39 16.05.2019] Printer status changed: from connecting to printing
[21:39 16.05.2019] Printer error: 201 : Error:Missing linenumber

[21:39 16.05.2019] Printer status changed: from printing to connecting
[21:39 16.05.2019] Printer status changed: from connecting to printing
[21:39 16.05.2019] Printer error: 201 : Error:Missing linenumber

[21:39 16.05.2019] Printer status changed: from printing to connecting
[21:39 16.05.2019] Printer status changed: from connecting to printing
[21:39 16.05.2019] Printer error: 201 : Error:Missing linenumber

It goes on like this endlessly.
Can I do anything to prevent these errors?

Thank you.

Could you try enabling verbose mode and Report Problem through 3DPrinterOS Client?