6.9.0 Firmware for Prusa CORE One+ (Gen 2) INDX, CORE One INDX

Summary

• New features

  • New Edition: C1+ (Gen 2) → INDX Conversion Support - Added support for converting the C1+ Gen 2 to INDX, including belt switching.
  • GT1.5 Belts - Added support for GT1.5 belts.
  • Expansion Joints Gen 2 - Added support for Expansion Joints Gen 2, featuring a significantly shorter heat-absorption phase on CORE One+ (Gen 2).
  • Automatic Nozzle Cleaner Calibration - Added automatic calibration of the nozzle cleaner.
  • Load All / Unload All - Added Load All and Unload All options to the Filament menu.
  • Filament Sensor Calibration - Added filament sensor calibration and improved handling of the “Not connected” state.
  • Crash Dump Saving - Added the option to save crash dumps after a Red Screen event via Settings > System > Save Crash Dump. Crash dumps can help diagnose and debug user-reported issues.
  • FLEX Material Current Profile - Added a dedicated current profile for FLEX materials (M906 P2).

• Improvements and Changes

  • Print State Bed Position - The bed now moves down after Empty Waste Bin, and when pausing, stopping, or finishing a print.
  • Tool Mapping Persistence - Tool mapping is now preserved when reprinting a job.
  • Chamber Grid - The chamber grid now closes automatically after a print is completed.
  • INDX Head LED Dimming - INDX head LEDs now dim together with the chamber light.
  • Menu Reorganization - Reorganized the menu structure for improved usability.
  • Nozzle Cleaner Resume - The nozzle is reheated in the nozzle cleaner when resuming a print.
  • Purge Point - Adjusted the purge point by +0.5 mm in Y.
  • INDX Nozzle Presence Detection - Relaxed the upper threshold for nozzle presence detection to improve detection reliability.
  • Ringdown Decay - Adjusted the "nozzle presence" decay treshold from 0.095 to 0.085.

• Fixes

  • Incorrect Temperature After Runout - Fixed an issue causing an incorrect nozzle temperature to be displayed after a filament runout.
  • Auto-Retract with Cold Nozzle - Fixed an issue where auto-retraction could be triggered with a cold nozzle.
  • Bed Position After Print State Changes - Fixed cases where the bed did not move to the expected position after pausing, stopping, or completing a print.

This is the stable release of firmware 6.9.0 for the Founders Edition Prusa CORE One/+ INDX, and Prusa CORE One+ (Gen 2) INDX. This release introduces firmware support for the new CORE One+ (Gen 2) hardware.

Note: Firmware 6.9.0 is compatible only with Founders Edition Prusa CORE One/+ INDX, and Prusa CORE One+ (Gen 2) INDX.

6.8.1 Firmware for Prusa CORE One L+, CORE One L, CORE One+ (Gen 2), CORE One

Summary

• New features
  • New editions: CORE One+ (Gen 2) and CORE One L+
  • Nozzle Wiper support, replacing the previous print-start nozzle cleaning routine
  • GT1.5 belts support
  • Expansion Joints Gen 2 support, with a much shorter Absorbing heat phase [C1+ (Gen 2)]
  • Immediate stop on filament runout
  • Guided calibration order - calibrations and tests declare their prerequisites
• Changes and improvements
  • Reorganized menus - some settings have been moved to different submenus
  • Filament compatibility checks in more places
  • Custom filament names may contain lowercase letters
• Fixes
  • Fixed not restoring original temperature on filament runout/mid-print change
  • More reliable communication with the xBuddy Extension
  • The last file in a folder was not visible, and related file list fixes
  • The printer no longer beeps on boot in Silent mode
  • An upward swipe on the touchscreen is no longer registered as a tap
  • And a lot more

This is the stable release of firmware 6.8.1 for the Prusa CORE One, CORE One+, CORE One+ (Gen 2), CORE One L and CORE One L+, introducing firmware support for the hardware of the new CORE One+ (Gen 2) and CORE One L+ editions, along with a reorganization of the on-screen menus, a guided calibration order and a number of fixes.

Note: This firmware 6.8.1 is not compatible with INDX

New editions: CORE One+ (Gen 2) and CORE One L+

Firmware 6.8.1 adds support for the hardware that ships with the new CORE One+ (Gen 2) and CORE One L+ editions: the nozzle wiper, the GT1.5 belts and the second-generation bed expansion joints (non-L only, L has an AC bed). Each is described in its own section below.

The edition is selected in Settings → Hardware → Edition, which applies all of its hardware options at once. The individual toggles remain available for printers that have been retrofitted with only some of the accessories.

Nozzle Wiper

Printers fitted with the Nozzle Wiper clean the nozzle by wiping it across the wiper pad at the start of a print. This replaces the Nozzle Cleaning routine, which removed debris by tapping the nozzle against the print sheet.

Note: A wipe can also be triggered manually with the G12 G-code. The wiper is enabled in Settings → Hardware → Nozzle Wiper.

GT1.5 belts

Printers now support the new GT1.5 belts and their transmission wheels, which move a slightly different distance per motor revolution than the original belts.

The belt type is set in Settings → Hardware → GT1.5 Belts. Changing it resets the belt tuning and the XY homing calibration, and restarts the printer.

It is important for the setting to match the actual belts installed. An incorrect setting makes prints come out dimensionally wrong and causes homing problems.

Expansion Joints Gen 2 [C1+ (Gen 2)]

The redesigned bed expansion joints let the frame reach a stable temperature considerably faster, so the Absorbing heat phase before a print can be shortened. With the second-generation joints enabled, the Absorbing heat is skipped entirely for bed temperatures up to 85 °C (PLA & PETG), and for higher bed temperatures the printer expects the frame to stabilize twice as fast, roughly halving the wait.

The joints are enabled in Settings → Hardware → Expansion Joints Gen 2.

Immediate stop on filament runout

When a filament runout is detected, the printer now stops immediately instead of first finishing the moves that are already queued. The end of the filament is therefore not driven as deep into the printer, where it could get stuck and be difficult to remove.

Guided calibration order

Calibrations and tests now declare which other calibrations they depend on. Starting one whose prerequisites have not passed yet shows a message listing which calibrations need to be completed first.

Reorganized menus

A number of settings have been moved to different submenus, and the order of items within some menus has changed. Most menus now also show a header icon.

• Input Shaper and Phase Stepping moved from Settings into Settings → Hardware
• Printhead moved from Settings → Hardware up into Settings
• Lights (formerly Lights Settings) moved from Settings → User Interface up into Settings
• Firmware Update (formerly FW update) moved from Settings into Info
• Belt Tuning (formerly Manual Belt Tuning) moved from Settings into Control → Calibrations & Tests
• Chamber Fans Limit moved from Control → Temperature into Settings → Hardware
• Display Refresh Speed moved from Settings → Hardware into Settings → User Interface
• Loaded filament moved from Filament → Manage Filaments up into Filament
• The Temperature menu is now Temperature & Fans

Filament compatibility checks in more places

The checks that compare the selected filament against the printer's hardware - for example an abrasive filament against a nozzle that cannot handle it - previously ran only when a print was started. They now also run when the filament is changed from the print preview screen, and in Change All Filaments.

Custom filament names may contain lowercase letters

Custom filament names were restricted to uppercase letters, digits, underscores and dashes. Lowercase letters are now accepted as well.

6.6.3 Firmware for Prusa CORE One+ INDX, CORE One INDX

Summary

• Improvements

  • Improved head LED behavior by synchronizing tool LEDs with the printer state and matching the status indication used by the heated bed LEDs.
  • Added Nozzle Cleaner Y Offset adjustment to the Tune menu for easier calibration directly from the printer interface.
  • Added ringdown decay information to the Sensor Info screen for improved diagnostics and troubleshooting.
  • Improved synchronization of loadcell samples between the toolhead and xBuddy, increasing the robustness of probing and calibration procedures.
  • Optimized motion step calculations to reduce the risk of layer shifts during printing.
  • Streamlined hotend management logic to improve maintainability and reliability.
  • Reduced calibration time by skipping temperature residency during tool offset calibration heating.

• Fixes

  • Reworked nozzle heater self-test validation to use thermal model evaluation during heating, reducing false self-test failures caused by minor deviations in heating performance.
  • Added validation of INDX coil current during heater self-tests to detect abnormal nozzle behavior.
  • Updated INDX nozzle thermal diagnostics to leverage thermal protection results for more accurate fault detection.
  • Fixed an issue where hotend thermal errors could be reported even when no nozzle was installed by verifying nozzle presence before triggering errors.
  • Fixed the Tool Change button incorrectly opening the extruded filament submenu.
  • Fixed an issue where an uninitialized nozzle temperature was displayed as 15 °C in the footer.
  • Removed a redundant cooldown check from the nozzle cleaner calibration process.

This is the stable release of firmware 6.6.3 for the Prusa CORE One+ INDX and CORE One INDX.

6.6.2 Firmware for Prusa CORE One+ INDX, CORE One INDX

Summary

• Improvements

  • Adjusted the nozzle cleaner origin position and fixed handling of nozzle cleaner offsets during parking moves.
  • EEPROM-stored nozzle cleaner offsets are now automatically adjusted after the update, eliminating the need for nozzle cleaner recalibration.
  • Adjusted the tool lock move distance for improved tool pickup reliability and reduced risk of filament being unintentionally ejected from the extruder gears.
  • Added a new option in the Tune menu for fine-tuning the nozzle cleaner X offset.

• Fixes

  • Fixed bumping into the waste bin after an MBL failure.
  • Fixed an issue requiring tool removal during Dock Calibration even when no tool was loaded in the head.
  • Fixed support for older xBuddy revisions with inverted pins (early MK4 converted boards). (Credit: @ScottKolo)
  • Fixed selftest gray buttons not updating after dependencies were met.
  • Fixed incorrect feedrate when loading PLA after FLEX material.
  • Fixed an invisible Abort button on the Y-axis Input Shaper selftest screen.
  • Fixed Tool Offset Cyphal communication not being reinitialized after board reset.

This is the stable release of firmware 6.6.2 for the Prusa CORE One+ INDX and CORE One INDX.

6.6.1 Firmware for Prusa CORE One+ INDX, CORE One INDX

Summary

• Improvements

  • Lower the print bed when a tool is unknown or lost, allowing the user to safely remove the print.
  • During Dock Calibration, users can now choose between Keep, Calibrate, and Invalidate.
  • Added an M109 flag to skip temperature stabilization.

• Fixes

  • Fixed spontaneous INDX Head resets.
  • Fixed incorrect tool assignment after a REDSCREEN reset. The printer now saves the currently selected tool.
  • Removed the extruder filament sensor from the footer and the Sensor Info menu.

This is the stable release of firmware 6.6.1 for the Prusa CORE One+ INDX, CORE One INDX.

6.6.0 Firmware for Prusa CORE One+ INDX, CORE One INDX

Summary

New features and improvements

• First firmware release for the Prusa CORE One/+ INDX
• Full INDX toolchanger support, with automatic tool changes for up to 8 tools
• Contactless nozzle induction heating
• Continuous nozzle presence detection for safety and fault detection
• Contactless tool offset sensor
• Guided INDX calibrations: docks, tool offsets, nozzle cleaner, and more
• Automatic, low-waste nozzle cleaning with a wastebin
• Screen for unloading or changing all filaments at once
• Reworked tool mapping screen supporting up to 8 tools
• Empty Nozzle Cleaner
• Known issues are listed at the end

This is the first firmware release for printers equipped with the INDX toolchanger, and it builds on the current firmware. It adds complete support for the INDX hardware, including automatic tool changes with up to 8 tools, induction heating, and a guided calibration workflow that takes you from assembly to your first multi-material print.

Welcome, INDX!

The INDX toolchanger, developed by Bondtech in collaboration with Prusa Research, transforms your CORE One/+ into a multi-material printer with up to 8 tools. The system combines a single active INDX Head with lightweight passive tools. Each tool consists of a filament path and a nozzle, with no heaters, wires, or electronics. After installing the conversion kit and flashing this firmware, the printer identifies itself as a CORE One+ INDX and guides you through the initial calibrations.

Both the 4-tool and 8-tool kit configurations are supported. The firmware lets you calibrate and enable any number of tools from 1 to 8, so you can run the printer with exactly as many tools as your print requires.

Induction heating with temperature compensation

The INDX Head heats the nozzle of the currently picked-up tool by induction and measures its temperature contactlessly. In addition, the firmware runs a thermal compensation model that accounts for extrusion speed, chamber temperature, print fan speed, and the thermal properties of the loaded filament, keeping the actual melt temperature on target across changing print conditions. The INDX Head also independently monitors its own temperatures, adding an extra layer of safety on top of the printer's standard thermal protections.
Because the nozzles heat up in seconds, the time required for temperature stabilization is significantly shorter than on a conventional hotend.

New contactless tool offset sensor

The new inductive sensor mounted on the print bed automatically measures each tool's XY offset, ensuring that every tool prints in perfect alignment. The tools are heated during the measurement process, compensating for slight changes in the thermal expansion of the metal nozzle.

Continuous nozzle presence detection

For safe and reliable multi-tool printing, the INDX Head continuously verifies that the picked-up tool's nozzle is present. It detects the nozzle through its induction system and re-checks it approximately every 100 ms while idle and every 500 ms while heating.
If a nozzle goes missing - whether because a tool has fallen off its dock or a pick or park operation did not complete successfully - the printer detects the issue and responds safely instead of heating or extruding without a nozzle in place. Ambiguous readings, such as a nozzle caught halfway, are treated cautiously and resolved by the system's recovery logic.

Guided INDX calibrations

The Calibrations & Tests wizard has been extended with new INDX-specific routines and guides you through the complete setup process in the correct order:

• Homing calibration: Reworked for the INDX toolhead with improved accuracy and repeatability. Invalid probes are detected and retried automatically, and the calibration pattern has been redesigned, which is essential for repeatable tool docking.
• Dock calibration: Fine-tunes the position of each dock to ensure the INDX Head can reliably pick up and park tools.
• Tool offset calibration: Measures the XY offsets of every tool using the new contactless inductive sensor, ensuring all tools print in perfect alignment. This calibration, including Z-offset measurement, runs at the start of every print to eliminate tool-to-tool alignment issues.
• Nozzle cleaner calibration: Aligns the nozzle cleaner and wastebin positions for reliable cleaning and blob ejection.
• Input Shaper and Phase Stepping calibration: Measures vibration compensation using the accelerometer built into the INDX Head.

Automatic, low-waste nozzle cleaning

The printer keeps every nozzle clean automatically. An integrated nozzle cleaner and wastebin handle a range of routines, from a quick wipe during tool changes to deep cleaning and purged-blob ejection, ensuring that color bleed and debris never reach your print. The entire system is designed around minimal waste: tool changes require only a very small purge, and the purged material is collected in the wastebin rather than ending up on the print bed or in a separate purge tower.

Empty Nozzle Cleaner

Allows you to easily empty the wastebin. It can automatically pause prints with a high number of tool changes (configurable under Settings > Nozzle cleaner).

A side filament sensor for every slot

Each tool slot has its own side filament sensor, allowing the printer to detect filament runout on a per-tool basis, which is essential for multi-material printing. A runout event triggers the standard filament-change process for the affected tool only.

New multi-tool filament management screens

Managing up to 8 filaments simultaneously is now easier:

• The filament change screen for multiple tools now offers "Set all to" to assign a filament type to all slots at once, and "Unload all" to clear the printer in a single operation.
• Unloading works even when the loaded filament type is unknown.
• Loaded filaments can be reviewed per slot, including nozzle diameter and high-flow nozzle settings for each tool.

Tool mapping and Spool Join

The features known from the Original Prusa XL are available here as well:

• Tool mapping lets you reassign which physical tool prints each filament from the sliced G-code, directly from the extended tool mapping screen on the printer or remotely via Prusa Connect. The screen is now scrollable to accommodate mapping of up to 8 tools.
• Spool Join automatically continues printing from another slot loaded with the same filament when a spool runs out.

Known issues

Pick / park failures

The INDX toolchanger can perform thousands of tool changes during a single print, and reliable picking and parking depend on accurately calibrated positions. If a pick or park operation fails, the printer automatically re-homes the tool and retries, which usually succeeds. In rare cases (for example, if a tool has fallen off its dock), multiple consecutive failures will pause the print for inspection. Once the print area has been checked, printing can be resumed seamlessly.

Parking in an occupied dock

In rare cases, the INDX Head may fail to park a tool while still passing the subsequent nozzle-presence check. The previously used nozzle may then continue printing until the system detects the issue.

Single-tool auto-load

Filament auto-load is supported, but currently only for the tool that is picked up.

Flexible materials

In some cases, TPU and other flexible filaments can tangle inside the INDX Head, causing the extruder motor to skip steps. We will continue fine-tuning the system to eliminate this issue.

Special materials

The thermal model uses thermal-capacity constants defined for known filament types. Special materials with different thermal properties may trigger a thermal runaway error.

Spontaneous INDX Head resets

The INDX Head may undergo internal resets, even during printing. This has no negative effect on print quality, but in rare cases side-effect errors ("Puppy errors") may occur. We are actively working to resolve this.

Phase Stepping & Input Shaper calibrations

These calibrations may occasionally encounter errors. In most cases, restarting the printer and trying again resolves the issue.

Filament stuck detection

Not available on INDX printers in this release.

6.5.7 Firmware for Prusa CORE One L, CORE One+, CORE One, MK4S, MK4, MK3.9S, MK3.9, MK3.5S, MK3.5

Summary

• New features and improvements
  • Improved filament change between different materials
• Fixes
  • Support for older xBuddy board versions
  • Fixed input shaper calibration for CoreXY printers
  • Fixed not loading custom Connect certificates
  • Fixed a crash when printing more than 1024 objects

This is the stable release of firmware 6.5.7 for the Prusa CORE One L, CORE One+, CORE One, MK4S, MK4, MK3.9S, MK3.9, MK3.5S and MK3.5 bringing targeted stability improvements and fixes.

Improved filament change between different materials

The filament change procedure has been improved to better handle switching between materials with significantly different print temperatures.

When loading the new filament, the printer now preheats to the higher temperature of the two materials. Once the filament is in the nozzle, the target temperature is adjusted to match the newly inserted material.

This allows the nozzle to cool down gradually when switching to a lower-temperature material, while the previous filament is purged out.

Fixed input shaper calibration for CoreXY printers

Input shaper calibration on CoreXY printers now correctly uses XY coordinates instead of AB coordinates. This fixes an incorrect excitation pattern that could lead to inaccurate calibration results.

Fixed not loading custom Connect certificates

Our customers can set up their printers to use non-official Connect servers by using the “Load Settings from File” menu item. This should also include loading a custom SSL certificate, which was however not working due to a bug in the firmware that has now been fixed.

Please note that we do not open-source our Connect backend infrastructure.

Fixed a crash when printing more than 1024 objects

We addressed a crash triggered when trying to print a G-Code file with more than 1024 objects.

6.4.2 Firmware for Prusa XL & MINI

Summary

• Fixes
  • Fixed not loading custom Connect certificates

This is the stable release of firmware 6.4.2 for the Prusa XL, MINI.

Fixed not loading custom Connect certificates

Our customers can set up their printers to use non-official Connect servers by using the “Load Settings from File” menu item. This should also include loading a custom SSL certificate, which was however not working due to a bug in the firmware that has now been fixed.

Please note that we do not open-source our Connect backend infrastructure.

6.4.1 Firmware for Prusa XL

Summary

• Improved phase stepping calibration
• Fixed homing issues with no tool picked
• Fixed toolchanger service moves being affected by user feedrate override
• Relaxed nozzle cleaning checks to prevent false nozzle cleaning failed errors
• Relaxed print fan selftest thresholds to reduce false failures
• Known issue - Power panic resulting in a BSOD

This is the stable release of firmware 6.4.1 for the Prusa XL bringing targeted stability improvements and fixes - most notably addressing several homing and toolchanging reliability issues.

Improved phase stepping calibration

The switch to the new universal phase stepping calibration in the 6.4 release caused a regression in the calibration quality for some XL users. In 6.4.1, the calibration method has been refined and further improved by backporting phase stepping fixes from the 6.5 releases. These changes enhance overall calibration reliability and address regressions introduced in earlier 6.4 builds.

Fixed homing issues with no tool picked

Homing without a tool picked could cause audible motor skipping or put the printer into an invalid state under certain conditions. The fix ensures that the axes are properly homed before attempting a tool pick, preventing both issues.

Fixed toolchanger service moves being affected by user feedrate

Tool parking, picking, and alignment moves could be slowed down if a low feedrate was set in G-code beforehand. This could lead to unreliable tool changes. All toolchanger service moves now run at their intended speeds regardless of the user feedrate setting.

Relaxed print fan selftest thresholds to reduce false failures

The print fan selftest could incorrectly report a failure on some units due to tight RPM thresholds that did not account for normal fan-to-fan variation across different fan shroud revisions. The thresholds have been relaxed to reduce false failures.

6.4.1-RC Firmware for Prusa XL

Summary

• Fixes
  • Phase stepping fixes from the 6.5 releases

This is the release candidate for the upcoming firmware 6.4.1 for the Original Prusa XL.

For a complete overview of features introduced in firmware 6.4.1, users can refer to the 6.4.1-beta published earlier.

Phase stepping fixes from the 6.5 releases

Phase stepping fixes from 6.5 have been backported to 6.4.1. This improves phase stepping and prevents regressions introduced in earlier 6.4 builds.