6.1.4 Firmware for Original Prusa MK4S

Summary

• Shipping Preparation Option for Factory Reset

This is a stable release of firmware 6.1.4 for the MK4S with MMU3. This update introduces a new feature primarily to support internal shipping needs, ensuring that the bundled printer and MMU3 unit is configured correctly out of the box. Users don’t need to install this update unless specifically advised, as it is intended mainly for manufacturing and shipping support without impacting regular printer functionality.

Shipping Preparation Option for Factory Reset

A new "Shipping preparation" option has been added to the Factory Reset submenu. This option enables a factory reset that also pre-configures the printer's “Nextruder type” settings in the EEPROM before the machine restarts. This ensures that, when the customer first starts up their machine, it displays the correct printer type (MK4S) and Nextruder type (“MMU”).
After receiving the printer, users must complete the full setup wizard with the MMU disabled. This is necessary to calibrate key components, such as the filament sensor, which is required to enable MMU. Once the wizard is completed, users can activate the MMU3 manually.

Full Changelog: v6.1.3...v6.1.4

6.2.0-alpha2 Firmware for Original Prusa MK4, MK4S, MK3.9, MK3.9S, MK3.5, MK3.5S, MINI & XL

Summary

• New features
  • “Set Ready” button
  • Connect header status icon
• Bugfixes
  • Fixed Wi-Fi regression
  • Fixed “/api/v1/job GET response contains invalid JSON” (public PR)
  • Fixed Accelerometer sometimes not being detected (MK4S)

This is a public release of the 6.2.0-alpha2 firmware for the Original Prusa MK4/S, MK3.9/S, MK3.5/S, XL, and MINI+.

This is an alpha release intended for experienced users. We’ve not been doing translations for changed/newly added texts yet. The features in this firmware are still under development and may not perform as expected. Should you encounter any bugs or issues with the printer’s performance, please report them via GitHub or in our forums.

Please note that this is a testing firmware developed primarily on stock unmodified printers. In case you are running any 3rd party upgrade, exercise caution and let us know in case of any issues.

New Features

“Set Ready” button

If your printer is set up in the Prusa Connect, you can now mark the printer as “Ready” directly from the print finish screen.

Connect header status icon

We added a new header icon, indicating Connect status:

• “C” when the printer is registered to the Connect (and grayed out when there is no network connection)
• “☑” when the printer is registered to the Connect and the printer is “Ready”.

Bugfixes

Fixed Wi-Fi regression

We have reverted the changes made to the Wi-Fi system in version 6.2.0-alpha1 and are currently investigating which specific change caused the issue with the printers not being able to connect to Wi-Fi

Fixed “/api/v1/job GET response contains invalid JSON” (public PR)

We have merged a public PR #4196 that fixes issue #4193 that was causing an invalid JSON response in the Prusa Link API endpoint “/api/v1/job”. Kudos to @ysmilda.

Fixed Accelerometer sometimes not being detected (MK4S)

We’ve fixed a bug where the Prusa Accelerometer was sometimes not detected during the first IS calibration after the printer started

Full Changelog: v6.2.0-alpha1...v6.2.0-alpha2

6.2.0-alpha1 Firmware for Original Prusa MK4, MK4S, MK3.9, MK3.9S, MK3.5, MK3.5S, MINI & XL

Summary

• New features
  • Expanded GPIO functionality (MK4/S, MK3.9/S, MK3.5/S)
  • Toolhead and hardware menu overhaul
  • Improved filament management
  • Nozzle information for Prusa Connect
  • Japanese language support on MINI
  • Mapping screen from Prusa Connect
• Community Contributions
• Bug Fixes
  • Wi-Fi stability improvements
  • G-code transfer fixes
  • USB media prefetch
  • Improved preview loading during file transfer
  • MINI sensor update fix
  • Persistent Compatibility Mode
• Model changes
  • CoreXY model calculations

This is a public release of the 6.2.0-alpha1 firmware for the Original Prusa MK4/S, MK3.9/S, MK3.5/S, XL, and MINI+.

This is an alpha release intended for experienced users. The features in this firmware are still under development and may not perform as expected. Should you encounter any bugs or issues with the printer’s performance, please report them via GitHub or in our forums.

Please note that this is a testing firmware developed primarily on stock unmodified printers. In case you are running any 3rd party upgrade, exercise caution and let us know in case of any issues.

Translation Status

While all language variants are available, we acknowledge that the translations are not yet fully complete. This is not a bug, and full translation support will be added in a future update.

New Features

Expanded GPIO functionality

The GPIO functionality has been enhanced in this release. While M260 and M261 API was already introduced in version 6.1.2, we’ve now added dedicated support for the Prusa-specific GPIO expander through G-codes M262 - M265.
These new G-codes extend the control over the GPIO expander, making it more versatile and powerful as we now support input on GPIO, allowing users to trigger custom-defined macros in G-code format, up to 1024 bytes in size. Full details on this feature, along with G-code usage examples, are available in our GPIO article.

Toolhead and hardware menu overhaul

The toolhead and hardware menu has been reworked, allowing users to set specific parameters for each individual toolhead and also for all of them at once. This also includes checks for hardened or high-flow nozzles, ensuring that your toolhead is always properly configured.

Improved filament management

We’ve revamped the filament management system, offering more customization and control for users:

• Hide filaments: Users can now choose to hide any filament types from the menus (e.g. preheat menu, filament load menu, etc.)
• Reorder filament: You can now manually change the order in which filament types appear.
• User filaments: Introducing user-defined filament options for more personalized settings.
• Custom filament Settings: Ad-hoc definition can now be made during the filament loading process, allowing you to tweak parameters - depending on loaded material.
• Abrasive materials warnings: If you’re working with abrasive materials (e.g., carbon or glow-in-the-dark filaments) without a hardened nozzle, the printer will now provide a warning during filament loading or print start.
• Loaded filament display: A new menu option “Loaded filament(s)” shows what filament is currently in use. Filament categories are indicated as Preset, User-defined, or Custom. On the MINI, some information is hidden due to screen size constraints.

Nozzle information for Prusa Connect

We’ve integrated detailed nozzle data into Prusa Connect, ensuring that users can now view nozzle-related parameters for all tools directly from the Connect.

Japanese language support on MINI

With this release, we’ve introduced Japanese as an official language option for Original Prusa MINI and MINI+ printers, allowing a broader global audience to interact with the machine more intuitively.

Mapping screen from Prusa Connect

This release introduces support for multi-tool filament mapping screen from Prusa Connect. While this feature is still in development and thus not fully functional, users will notice incremental updates as we continue to integrate these tools.

Community Contributions

We would like to extend our gratitude to the Prusa community for their invaluable contributions to this release. The following improvements were made by community members:

• Enable DNS for SNTP Client: DNS support for the SNTP client has been enabled, and the default server is now set to prusa3d.pool.ntp.org (thanks to @thess via #3730).
• Quoted INI String Support: Support for quoted INI string values has been added (contributed by @nmschulte via #3158).
• Experimental Serial Printing Screen: A new experimental option has been added to disable the serial printing screen (contributed by @PinkPandaKatie via #4071).
• Trailing Zeroes Fix: Fixed an issue where trailing zeroes were incorrectly displayed in the footer (thanks to @puhitaku via #4129).
• German Translation Fix: The German translation has been improved (contributed by @foorschtbar via #4136).
• XL Debugging Improvements: Enhanced debugging features for the Original Prusa XL (thanks to @vintagepc via #3419).

We would also like to take this opportunity to thank the community for submitting crash dumps. These reports have been critical in helping us identify and resolve bugs, and we are pleased to note that crash reports have significantly decreased over the past two months.

Bug Fixes

Wi-Fi stability improvements

Several bugs related to Wi-Fi connectivity have been addressed, including crashes caused by high outgoing traffic. This should improve overall network stability during data-intensive tasks.

G-code transfer fixes

We’ve resolved issues causing BSODs at the end of G-code transfers with specific file sizes. Additionally, we’ve improved the process for cleaning up failed transfers to prevent clutter and reduce potential errors.

USB media prefetch

A media prefetch feature has been overhauled, addressing recurring USB errors by improved handling of data during the print process. This should result in fewer connectivity issues during printing.

Improved preview loading during file transfer

We've optimized the print preview during file transfer from Prusa Connect. Previously, the preview appeared only after 50% of the file was downloaded, even though the necessary data was available earlier. This fix improves polling frequency and task prioritization to ensure faster preview generation and quicker print start times.

MINI sensor update fix

The MINI previously failed to update sensor statuses correctly. This has now been fixed, ensuring that users receive accurate sensor data during operations.

Persistent compatibility mode

We have addressed an issue where the compatibility mode settings were not properly stored or restored after a power panic procedure was triggered.

Model adjustments

CoreXY model calculations

The CoreXY physics model has been revised to better align with the actual physical system, ensuring more accurate and consistent movement calculations.

Known Issues and Regressions

Wi-Fi throughput regression

We’ve identified a potential regression where Wi-Fi throughput may have decreased. We are actively working on a fix and will include it in an upcoming update.

6.1.3 Firmware for Original Prusa MK4, MK4S, MK3.9, MK3.9S, MK3.5, MK3.5S & XL

Summary

• Issues with numeric keyboard repaired (MK4/S, MK3.9/S, MK3.5/S, XL)
• Returned nozzle diameter setup (XL)
• Printhead position during calibrations changed (MK4/S, MK3.9/S, MK3.5/S)
• Cold pull (XL)

This is the stable release of firmware 6.1.3, which adds cold pull support for the XL, fixes bugs, and restores functions that were removed in the previous version.

Issues #4149 numeric keyboard repaired (MK4/S, MK3.9/S, MK3.5/S, XL)

There was an issue with setting numerical values for nozzle temperature, bed temperature, and print fan speed using the on-screen keyboard. Although the values appear correctly in the menu after input, the settings do not actually take effect—resulting in the fan not turning on or the temperatures not being applied. This problem did not occur when using the scroll knob to set these values.

Note: It is currently not possible to control the extruder motor movement via the on-screen keyboard.

Returned nozzle diameter setup #4151 (XL)

In version 6.1.2, the option to set the nozzle diameter on XL printers was unintentionally removed. We've acknowledged the oversight and have now restored this functionality in the latest update, allowing users to adjust the nozzle diameter settings once again.

Printhead position during calibrations changed (MK4/S, MK3.9/S, MK3.5/S)

Adjusted the print head position during printer calibrations to prevent it from colliding with the spool in the enclosure, ensuring smoother and safer calibration processes.

Cold pull (XL)

The Cold Pull method is a popular method used for unclogging or cleaning your extruder. Starting from this release, you can take advantage of a new feature that will guide you through the entire process using a step-by-step Wizard and provide assistance.

Full Changelog: v6.1.2...v6.1.3

6.1.2 Firmware for Original Prusa MK4, MK4S, MK3.9, MK3.9S, MK3.5, MK3.5S, MINI & XL

Summary

• Support for MK3.9S and MK3.5S printers
• Numeric keyboard
• Custom names for steel sheet
• User-configurable hostname
• Binary G-code check
• ESP firmware flash during boot (MINI, MK3.5/S, MK3.9/S, MK4/S)
• New bootloader 2.3.5
• Network Status screen
• Steel sheet name in footer (MK3.5/S)
• Powered Z-motors during calibration procedure (MK3.5/S, MK3.9/S, MK4/S)
• Default nozzle diameter set to 0.4 (XL)
• Bug fixes

This is the stable release of the firmware 6.1.2 adding support for upcoming printers. There are also multiple upgrades and improvements for the existing printers.

Note: This firmware 6.1.2 is a direct successor to the firmware 6.1.0. Version 6.1.1 won't be released to public as a major bug was found and is fixed in 6.1.2.

Support for MK3.9S and MK3.5S printers

This release extends compatibility with the latest printer models, ensuring access to new features for MK3.9S and MK3.5S printers.

Numeric keyboard

You can now use a numeric keypad to enter numerical values by simply touching and holding the adjustable numeric field value, e.g. move axis or nozzle temperature.

Custom names for steel sheet

Users can now assign custom names to their steel sheets via touch keyboard.

User-configurable hostname

Users can now define their own hostname for the printer.

Binary G-code check

A new binary G-code validation process has been implemented, which enhances the security and reliability of print operations. This feature checks the integrity of binary G-code blocks during printing.

ESP firmware flash during boot (MINI, MK3.5/S, MK3.9/S, MK4/S)

Flashing the ESP module now occurs automatically during each boot if the firmware version doesn't match, eliminating the need for manual updates via the menu. The runtime process that previously handled this has been completely removed. Now, if an ESP module is inserted during printer startup, it will be automatically flashed with the new firmware without any prompts.

New bootloader 2.3.5

Fixes the issue where the .bbf file was being requested on the USB drive for MINI printers.

Network Status screen

A new Settings menu screen that gathers the most important information about network status and connectivity to key servers.

Steel sheet name in footer (MK3.5/MK3.5S)

For MK3.5 and MK3.5S printers, the name of the currently loaded steel sheet is now displayed in the footer of the user interface.

Powered Z-motors during calibration procedure (MK series)

During the gearbox calibration process, the Z-motors will now remain powered, leading to more accurate and consistent calibration results. The motors are then powered off again after the calibration is completed.

Default nozzle diameter set to 0.4 (XL)

The default nozzle diameter setting for the XL model has been adjusted to 0.4mm.

Bug fixes

• fixed M73 report #4089
• fixes for unexpected USB disconnection

Improvements by the Prusa community

Thanks to the active community members who contributed their code to this release:

• Implementation of M260 and M261 (I2C Send/Request) by @rbuehlma via #3840
• Implementation of MK3 compatibility for G90 by @bkerler via #3865
• Increase nozzle size range in settings by @bkerler via #3699
• Provide feedback on loading settings from file by @bkerler via #3769
• Improvements to build scripts by @bkerler via #3582
• Improvements to github issue template by @murk-sy via #3298
• Fix of M300 (Play Tone) by @bkerler via #3686
• Fix of unnecessary filament loading on early abort by @krx via #4031
• Fix of French translation by @aginies @teotwaki and @bgiot via #3703
• Fix of Czech translation by @hawwwran via #4002
• Fix of German translation by @bkerler via #3614

6.1.0 Firmware for Original Prusa MK4S

Summary

• Original Prusa MK4S printer support
• Prusa app
• New Wi-Fi wizard
• Input Shaper calibration with accelerometer
• GPIO board support
• Improvements by the Prusa community

This is the stable release of firmware 6.1.0 introducing new printer MK4S and related features. For more information regarding the MK4S release, please read the Prusa blog post.

Note: This release is only for the MK4S printer. Firmware for other printers will be released separately in the near future.

Prusa app

Together with the MK4S release, we are also releasing a native application for your mobile device. This app allows you to use Prusa Connect with your printer and also helps with the initial setup, which is described in detail in the next section.

Prusa app is supported for the Android and iOS devices:

• Google Play: download link
• Apple Appstore: download link

New Wi-Fi wizard

This release introduces improved Wi-Fi Wizard. We've added a streamlined way to connect your printer to a Wi-Fi network. Below, you'll find the key features and methods available to set up your connection:

• Wi-Fi Setup via Touchscreen: Users can now manually enter Wi-Fi credentials directly on the printer using the touchscreen. The on-screen keyboard has a layout optimized for the limited display space.
• Network Scanning: The printer can scan for available Wi-Fi networks and display a list of results. Users can select a network and enter the password using the touchscreen keyboard.
• NFC Support with Prusa application: Wi-Fi credentials can be set up using the Prusa app on NFC-enabled mobile devices. The app writes the credentials to the printer via NFC, and the printer will prompt for confirmation before storing the information.
  All previously available methods for setting up Wi-Fi credentials are still supported.

These updates improve the ease of connecting your printer to a Wi-Fi network, providing multiple methods to suit your needs.

Input Shaper calibration with accelerometer

Our printers are pre-configured with optimized Input Shaper values from the factory. However, if you decide to make significant changes to your printer (e.g., by installing a mod on the Nextruder), you might need to recalibrate these values. For such opportunities, we’re launching an optional accelerometer accessory, so you can calibrate your printer. More information will be provided soon.

GPIO board support

We added support for our brand new hackerboard - a GPIO expander for xBuddy. This release currently supports output configuration through G-CODE in the print file. Input commands are in progress and will be included in the next release. More information will be provided soon.

Improvements by the Prusa community

Thanks to the active community members who contributed their code to this release:

• Implementation of M260 and M261 (I2C Send/Request) by @rbuehlma via #3840
• Implementation of MK3 compatibility for G90 by @bkerler via #3865
• Increase nozzle size range in settings by @bkerler via #3699
• Provide feedback on loading settings from file by @bkerler via #3769
• Improvements to build scripts by @bkerler via #3582
• Improvements to github issue template by @murk-sy via #3298
• Fix of M300 (Play Tone) by @bkerler via #3686
• Fix of unnecessary filament loading on early abort by @krx via #4031
• Fix of French translation by @aginies @teotwaki and @bgiot via #3703
• Fix of Czech translation by @hawwwran via #4002
• Fix of German translation by @bkerler via #3614

6.0.4 Firmware for Original Prusa MK4, MK3.9, MK3.5, MINI & XL

Summary

• Modified MCU overheat (XL)
• Bug fixes

This is a stable firmware release 6.0.4 that fixes bugs discovered during testing, as well as reported by the Prusa community.

Modified MCU overheat

If an MCU overheat occurs, the printer will first warn you and allow you to continue. If the MCU temperatures do not improve, the printer will display an error. The MCU overheat can be caused by higher ambient temperatures. See the 3D Printing Handbook for more information.

Bug fixes

• 1st layer calibration being stuck when using MK3.5 with MMU with unloaded filament reported on GitHub #4073. Previously, calibration was stuck because the MMU slot was unspecified when the filament was unloaded before starting calibration. Now we load filament into the first MMU slot. To use a different slot, load the filament manually and then start the calibration.
• Reproducible crash when using M300 G-code for playing sounds with certain frequencies. Reported on GitHub #4050. The crash was fixed, but the audio is still incorrect on XL. (This will be properly solved in some later version.)
• PrusaLink getting stuck on basic authentication, reported on GitHub #3705.
• Rare crash when a certain printer state changes too fast for GUI to notice, reported on GitHub #4052 and #4077.
• Printing times displayed on the printer now match the times estimated in PrusaSlicer.
• M300 G-code not waiting when playing sounds, reported on GitHub #3660. Fixed by community contributor @bkerler

Full Changelog: v6.0.3...v6.0.4

6.0.3 Firmware for Original Prusa MK4, MK3.9, MK3.5, MINI & XL

Summary

• Interim solution of USB disconnect issues (MK4, MK3.9, MK3.5, XL)
• PINDA off-bed probing repaired (MK3.5)
• Screenshot procedure fix (MINI)

Interim solution of USB disconnect issues (MK4, MK3.9, MK3.5, XL)

The developers have thoroughly reviewed the part of the firmware responsible for unexpected USB disconnects, which lead to print interruptions that cannot be resumed. As a quick hotfix, we have added the option to continue printing after this interruption.
However, we will continue to seek a definitive solution to this problem.

PINDA off-bed probing repaired (MK3.5)

Moved bed leveling probing points to avoid probing measurements out of the heatbed area. This issue was reported on GitHub as #3851.

Screenshot procedure fix (MINI)

Fixed an issue where the screenshot procedure ended with a blue screen of death (BSOD).

Full Changelog: v6.0.2...v6.0.3

6.0.2 Firmware for Original Prusa MK4, MK3.9, MK3.5, MINI & XL

Summary

• Original Prusa XL Enclosure functions (XL)
• Improvements by Prusa community

This is a stable firmware release 6.0.2 with Original Prusa XL Enclosure and its additional functions. It also fixes issues discovered during testing, as well as those reported by the Prusa community.

Original Prusa XL Enclosure functions (XL)

The XL Enclosure is designed to be seamlessly integrated with the rest of the printer. Not just the physical parts, but also the software, a new menu becomes available on the LCD touchscreen called Enclosure. Because the Enclosure is directly connected to the mainboard of the printer, you can configure a number of useful features. You can set up the filtration performance and even post-print filtration duration (e.g. when you print from materials such as ASA or PCCF) so that the system runs for additional time to filter out all particles produced during the print job. For more information, read this article.

Enabling the XL Enclosure in the menu
You can enable the XL Enclosure by going to Control -> Enclosure (Enable) on the printer. Then, run a fan connection test to verify that everything works. After that, you will see the Enclosure menu.

Features

• Filtration When you have enabled Enclosure and Print Filtration, the fan will operate at 80% of RPM. You can adjust the filtration performance in the menu (from 50% to 100%) during a running print job.

• Post Print Filtration You can also enable Post Print Filtration in Control -> Enclosure -> Manual Settings -> Post Print Filtration. When certain filaments (ASA, ABS, PC, FLEX, HIPS, PP) are detected in the G-code, the filtration will run for an additional 10 minutes to filter out all particles produced during printing. You can adjust the Post Print Filtration setting from 1 to 10 minutes..
  Note: PLA/PETG prints do not require post-print filtration.

• MCU Cooling The MCU checks the temperatures of the electronic boards on the Original Prusa XL.
  MCU Cooling has the highest priority and activates automatically (fan at 100%) when the enclosure is powered on. MCU cooling is activated when temperatures of any electronic board exceed 80°C and stops cooling at 75°C, regardless of whether printing is in progress. This is to protect internal electronics from overheating and to extend their lifespan.

• Temperature Display You can display the temperature inside the enclosure in the footer by going to Settings -> User Interface -> Footer. The temperature value is derived from the current or first tool board temperature. The temperature will be displayed 5 minutes after the start of printing. This delay is due to the need for temperature stabilization inside the XL Enclosure. The temperature will reset to “–” after the print is complete.

• Filter Expiration Tracking The enclosure tracks the active filtration time (not print time). After 500 hours, a dialog alerts the user that the filter will expire in 100 hours (the estimated lifespan is 600 hours of runtime). The dialog will let you choose from [IGNORE] - which will remind you before every print to change the HEPA filter, [POSTPONE] - which will postpone the dialog for 5 days, and [DONE] - which means that the HEPA filter has been changed and will restart the filter counter. After 600 hours, a dialog suggests changing the filter with a link to prusa.io/xl-filter.

• Fan Error Check will alert the user to check the fan connection and cleanliness if the fan isn't spinning as it should.

• Fan Connection Test will check if the fan is properly connected. This test runs whether you enable the enclosure from the menu or start the print.

Improvements by Prusa community

• Community translation correction #4002
• Community translation correction #3614

Community contributors @bkerler @hawwwran

Full Changelog: v6.0.1...v6.0.2

6.0.1 Firmware for Original Prusa MK4, MK3.9, MK3.5, MINI & XL

Summary

• Japanese language support (MK4, MK3.9, MK3.5, XL)
• Phase stepping fixes (XL)
• Nozzle cleaning repaired (MK4, MK3.9, XL)
• Acceleration limit restored (MK4, MK3.9, MINI)
• Stealth mode corrected (MK4, MK3.9, MK3.5, XL)

This is a stable firmware release 6.0.1 that adds one more language and fixes some issues discovered during testing, as well as reported by the Prusa community.

Japanese language support (MK4, MK3.9, MK3.5, XL)

Together with our team in Japan, we have translated the entire Buddy firmware into Japanese. The firmware will be utilizing Katakana. While implementing all the characters we encountered some interesting challenges. For example, Latin characters are typically more rectangular (taller than wider), whereas Katakana characters are closer to square in shape. This required some adjustments in the firmware.

The Japanese language is currently available for most of our printers on the Buddy platform, the only exception is MINI/MINI+ which requires further optimizations. We expect support for the MINI in the upcoming firmware release.

To our Prusa community in Japan ハッピー・プリンティング！

Phase stepping fixes (XL)

The developers have thoroughly reviewed the part of the firmware responsible for phase stepping and identified some edge cases occurring during operations such as homing, layer changes, filament changes, and tool changes on the XL.

Now, these specific edge cases are fixed and there should no longer be any skipped layers after the G-code M600 (filament change), and the XL tools should always be parked correctly.

Nozzle cleaning repaired (MK4, MK3.9, XL)

The nozzle cleaning process sometimes resulted in an error “Nozzle cleaning failed” due to a bug introduced in firmware 6.0.0. This bug caused the load cell buffer to "underrun," leading to an incorrect calculation of the distance between the tip of the nozzle and the heatbed. This error has now been fixed, and the nozzle cleaning feature should perform correctly again.

Acceleration limit restored (MK4, MK3.9, MINI)

Firmware 6.0.0 accidentally lowered the HW limit for acceleration and jerk in Normal mode, this release returns the limit to its original value.

Stealth mode corrected (MK4, MK3.9, MK3.5, XL)

In some scenarios, the firmware was not able to switch back to the Normal mode, this is now fixed.