Firmware updater is now part of the Slic3r PE, starting version 1.40.1. In case you have it already installed, you can skip to the next step.
  • Firmware updater is now part of the Slic3r PE, starting version 1.40.1. In case you have it already installed, you can skip to the next step.

  • Go to and select your printer.

  • Find the driver section and download the latest package. Leave this page opened for the next step!

  • Install drivers on your Windows, macOS or Linux system.

  • Part of the driver's package is Slic3r PE, which includes a tool for firmware upgrade.

In Step 1 Download necessary software

The instruction “Install drivers on your Windows or MacOS system” is not sufficient for MacOS. After downloading, the folder “prusa3d_mac_2_1_4” is left in the Downloads folder. Apparently it needs to be manually moved to the Applications folder to complete the installation.

Bill Waring - Reply

Hi Bill,

yes to install apps on MacO you need to move them to the applications folder. The guide assumes you know what to do, as this is a basic task on both operating systems.

Jakub Dolezal -

Seems like the drivers page has been updated, doesn’t look anything like the sample image anymore.

Evan - Reply

Hi Evan, yes you are right, the guides will be updated shortly.

Jakub Dolezal -

Go back to to get the firmware for your printer.
  • Go back to to get the firmware for your printer.

  • Download the zip file with the firmware to your computer and unzip it.

  • For the Mini RAMBo used in MK2/MK2S/MK2S MMU/MK2.5 you have to choose the firmware based on the version of the board you have. Inside the package there will be two files with either RAMBo 13a or RAMBo 10a in the name.

    • RAMBo 13a - used in the majority of the MK2 and all MK2S printers (most common). LCD connectors are part of the board.

    • RAMBo 10a - used in the MK1 and some early batches of MK2 (very rare). LCD connectors are outside the board.

    • More info about the boards used in MK2 a MK2S can be found in this PDF file (also enclosed in the firmware package).

    • More info about the boards used in MK2.5 can be found in this PDF file (also enclosed in the firmware package).

  • For the MK3 there is only one version, no need to choose.

For the firmware, it lists various .hex files, but I can’t find the English one.

Joe O. - Reply

  • Open Slic3r PE and from the menu select Configuration ->Flash Printer Firmware

  • Connect the printer to your computer using the bundled USB cable and select it from the menu. Hit Rescan if the printer is not on the list

  • Select the firmware file on your harddrive (*.hex). Do not place the firmware on a network share.

  • Hit the Flash button.

  • Wait until the process is completed. You can click on "Advanced: ..." to see the flashing process including detailed log.

  • When the flashing process is done, you will be informed.

  • We're done here! Your printer is ready to rock ;)

  • In case of issues with flashing the firmware please visit our troubleshooting article.


If Flash fails, try running Slic3r PE as Administrator.

Gerhard Wildzeisz - Reply

Thanks Gerhard for the tip ;)

Jakub Dolezal -

On Linux try launching Slic3r PE’s AppImage with sudo. Not ideal, but helped me resolve “Permission denied” issues.

Sergiy Byeloyzorov -

If it fails on Linux, try adding your user to the “dialout“ group by running “adduser <username> dialout“ as root. Depending your distro your user may already be a member of that group by default, but at least on Debian this is not the case from my experience.

Manolis Agkopian - Reply

I had to manually update the drivers from control panel in win7 64bit. Point it to the main Prusa3D install folder and you’re GTG.

Eric Bass - Reply

Hi, got a problem here.

Copyright (c) 2007-2014 Joerg Wunsch

System wide configuration file is "C:/PROGRA~1/Prusa3D/Slic3rPE/resources\avrdude\avrdude.conf"

Using Port : COM12

Using Programmer : wiring

Overriding Baud Rate : 115200

avrdude: ser_open(): can't open device "\\.\COM12": The system cannot find the file specified.

avrdude done. Thank you.

Can anyone help flash the firmware ?

Got the drivers working, windows had problems seeing the printer, but updated from installed folder and it’s ok now

GrigoreMihai - Reply

Hi there Grigore, check out this article hope that helps :)


Tomáš -

I can’t find the English .hex file in the list of .hex files.

Joe O. - Reply

Hi there, not sure where you were looking for the firmware .hex files. Yet if you go at this link and then click on Download 3.3.1. you shall download firmware for the MK3 with only one .hex file which is for english version. Hope this helps.


Tomáš -

I appreciate your assistance. I was trying to download the MK 2.5 firmware. When I open up the zip file, there is a list of hex files. I couldn’t find a n English one.. I finally figured out that they all had English with a designated second language. I was able to get it and all is fine, now.

Joe O. -

Finish Line

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Josef Prusa

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GNU/Linux Users, you can upload hex file using avrdude.

- Install arduino from your distro repos (Tested on Ubuntu 12.04)

- Download your new firmware for your board from:

- Extract

- Open a terminal and cd to extracted dir

- Upload by running (Change "3mm-RAMBo13a-PrusaNmk2.hex" to your board and extruder):

/usr/share/arduino/hardware/tools/avrdude -C/usr/share/arduino/hardware/tools/avrdude.conf -v -patmega2560 -cstk500v2 -P/dev/ttyACM0 -b115200 -D -Uflash:w:3mm-RAMBo13a-PrusaNmk2.hex:i

Alejandro Romero - Reply

Under Linux I flashed the firmware .hex file with avrdude:

avrdude -c stk500v2 -b 115200 -p Atmega2560 -v -P /dev/ttyACM0 -D -U 1_75mm_MK2-RAMBo13a-E3Dv6full-3.0.8.hex

Even better would be compiling the firmware myself, but so far the Arduino project didn't want to be built..

Jonas Jelten - Reply

I confirm it is working with avrdude on OSX too. Just uploaded doing: avrdude -c stk500v2 -b 115200 -p Atmega2560 -v -P /dev/tty.usbmodemFA131 -D -U 1_75mm_MK2-RAMBo13a-E3Dv6full.hex

To install avrdude: brew install avrdude --with-usb

Denis Pitzalis - Reply

You guys saved me here!....

With standard Arduino software install I was able to do:

$ pwd


$ ./avrdude -C ../etc/avrdude.conf -P /dev/tty.usbmodem1421 -b115200 -D -Uflash:w:/Applications/Prusa3d/prusa3d_mac_1_7_5/1_75mm_MK2-RAMBo13a-E3Dv6full.hex -v -patmega2560 -cstk500v2

and now my printer is back to normal...

Devon Heron - Reply

Anybody get continuous timeout messages doing this? This is from a Raspberry Pi running OctoPrint. I did hit the "disconnect" button in the OctoPrint web interface to try to prevent port conflicts.

pi@octopi:~ $ avrdude -c stk500v2 -b 115200 -p Atmega2560 -v -P /dev/ttyACM0 -D -U flash:w:1_75mm_MK2-RAMBo13a-E3Dv6full.hex:i

avrdude: Version 6.1, compiled on Jul 7 2015 at 10:29:47

Copyright (c) 2000-2005 Brian Dean,

Copyright (c) 2007-2014 Joerg Wunsch

System wide configuration file is "/etc/avrdude.conf"

User configuration file is "/home/pi/.avrduderc"

User configuration file does not exist or is not a regular file, skipping

Using Port : /dev/ttyACM0

Using Programmer : stk500v2

Overriding Baud Rate : 115200

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_ReceiveMessage(): timeout

avrdude: stk500v2_ReceiveMessage(): timeout

Henry Berg - Reply

I am getting this error:

Uncaught node.js Error

Error: EROFS, open '.fw.hex' at Error(native)

I am running Mac 10.12.3

I happen to have Node v4.6.2 installed

Richard Yee - Reply

Same error as @RichardYee, same Mac OS version 10.12.3, node version v5.10.0. What is the resolution?

Soumitra Kumar - Reply

I am also seeing the same Error: open 'fw.hex' message as mentioned above. On macOS 10.12.3, node v6.9.1.

Joe Fiorini - Reply

I tried the FirmwareUpdater on Win10 but the utility was unable to locate any com ports. I tried various thing spending almost a day until I found solution:

1) Remove the PRUSA 3D printer drivers in control panel, under printers & devices.

2) Remove all remaining PRUSA related software in control panel, under Programs and functions.

3) Turned off PRUSA i3 Mk2 and rebooted PC

4) Downloaded 1.7.6 windows drivers and installed them, using RMB and selecting Run as ADMINISTRATOR

5) Turned on PRUSA i3 Mk2

Now the Firmwareupdater found the COM ports and I could update firmware.

Per Hassel Sørensen - Reply

I had a problem with the FirmwareUpdater on macOS, so I just used avrdude as recommended in the comments. I did have to make one change though. After installing with brew install avrdude, the command I used was:

avrdude -c avrispmkII -b 115200 -p Atmega2560 -v -P /dev/tty.usbmodemXXXX -D -U 1_75mm_MK2-RAMBo13a-E3Dv6full.hex

You will need to look at what /dev/ device you should use. Try ls /dev/tty.usbmodem* to see it.

Andrew Willis - Reply

On linux I use Cura to load the FW file. Quick, easy, without problems.

In avrdude I had an error "avrdude error: stk500v2_ReceiveMessage (): timeout"

Łukasz Zep - Reply

I had to disconnect then delete my printer from the windows 10 settings page plug it back in again. Check its actually connects using Pronterface then run the Firmware updater which doesn't list my printer just Com3 comes up worked fine after that

Neil Winstanley - Reply

Do I have to check the Use relative E distances box in the prusa edition Slic3r?

Joaquin Otero - Reply

Hi Joaquin, "Use relative E distances" is checked by default. This thread is dedicated to the firmware update, next time please use the right section, our forums or support, thanks :)

Jakub Dolezal -

My os is Linux Mint 18.1. I used cura 3.1.0 for update to MK3 firmware 3.1.1.-RC5.

Update was easy, unzip, select hex file in cura “upload user defined firmware”. Selected printer was prusa MK2.

Meteor42 - Reply

The Prusa 3D Printing Handbook (from ) says that “First Layer Calibration ​is required after the firmware update“. Why isn’t this mentioned here also?

Kari Söderholm - Reply

Hi Kari, “first layer calibration” isn’t required after each firmware update. I will talk to my colleagues responsible for the Handbook to correct it.

Jakub Dolezal -

Upgraded successfully on Debian using avrdude, calibration didn’t run on reboot so I started it manually. Everything was fine until first layer calibration at which point it repeatedly failed on point 8. I couldn’t find any reason for this however a factory reset and starting the calibration wizard over fixed this. Thanks for the update :-)


Tom Hinkley - Reply

Can someone please help me? I have installed the new firmware as instructed, and now our Prusa MK2 is not responding, only turns on to a blank screen. I have tried a hard reboot and resetting to older version of the firmware. Please help we are hosting the 3D printer as part of a traveling technologies bundle for our area libraries.

Thanks Crystal

Crystal Vargas - Reply

Hi Crystal, blank screen might be some HW issue, please visit and look for the live chat button.

Jakub Dolezal -

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