When trying to upload firmware I get the following errors:

  1. timeout - cannot sync, or
  2. port is in use

What can be the possible sources of these errors?


1 Answer 1


There are mainly three reasons for that:

  1. Arduino studio settings should be:
    • Board: Mega 2560 and
    • Programmer: AVR ISP
    • and valid COM port, please see below:

Arduino settings

  1. Please close all slicer's instances (Cura, Slic3r, Repetiter) and host servers and other software that communicate with the printer as they lock the COM port;

  2. Please check that the appropriate usb2serial drivers are installed and working - the best way is to start the serial monitor from the Arduino Studio Tools menu and see if there are any.

  • 1
    $\begingroup$ +1 for mentioning the slicer software in the overview, the slicer is frequently overlooked and certainly got me a few times wondering why it would not upload! $\endgroup$
    – 0scar
    Commented Apr 20, 2018 at 9:05
  • $\begingroup$ how about a too-high baud rate? $\endgroup$
    – Roger
    Commented Apr 20, 2018 at 12:17
  • $\begingroup$ @Roger the baud rate is determined by board/programmer in Arduino Studio, that means we don't have access to set it. $\endgroup$
    – profesor79
    Commented Apr 20, 2018 at 12:26
  • 1
    $\begingroup$ 4. There is a preloaded task in your Arduino, I´ve seen this several times. $\endgroup$ Commented Apr 20, 2018 at 18:17

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