XL firmware 6.4.0 alpha  

RE: XL firmware 6.4.0 alpha

Hmm, For me since the release everything works fine. 

What I did: 

Flash the new firmware then

switched the machine off and on again. (to really have a clean restart)

doing x/y Calibration.

calibrating the toolheads (with the pin) 

Then started printing with all toolheads. Works perfectly, smooth and clean.

Crash detection is on. Silent mode is off. Input shaping is on. 

BTW: If I am in need for help, usually for me it mostly works out to ask for an engineer by phone. (Well except you have one of those Scriptbook-Lubbers on the other end of the line) 

Is there any engineer of Prusa reading this thread? - Give me a "Beep"... (I bet a good Swiss beer sent to prague on my expense, there will be no Beep)

RE:

It's not just alpha - the so-called "stable" release (6.4.0+11974, released on November 25) continues to have the bug. I just flashed the firmware (i.e. last night), and already suffered two crashes:

1. when I tried to park tool #1 - instead of going back to its dock, the tool veered to the right, and crashed into tool #2 with a vengeance, throwing tool #2 out of its dock. It happened so fast that I didn't have time to press the Reset button;

2. when I tried to calibrate the IS (Input Shaper) - the carrier locked tool #1 as it should, but then smacked to the right without first pulling the tool out of its dock. Nothing broken, though. (...Yet!)

I went back to the older firmware (6.2.6). While many features in the new firmware are desired, I don't want that piece of crap (i.e. firmware 6.4.0) to destroy my prints...or even worse, the printer itself. I'll wait until (and I'm saying it un-apologetically) the boneheads tweaking the firmware will get their act together, and release a working, bug-free version. For a $3,000+ printer this is unacceptable.

(P.S. I'm sending my comments to Prusa's customer service, too, so they're aware of the sentiment of (at least) one of their customers.)

RE: XL firmware 6.4.0 alpha

Interesting. 

What Version of Prusa-Slicer are you running on? - I run the newest version without any entry or exitcodes.

Did you a restart/ xycalib/ Toolheadcalibration?

Did the sledge loudly bump into the front/left block during calibration? 

If it did  chances are high, it glitched something. Then rerun the calibration from the other onscreen-menue. For me it works after a calibration without bumping.

Hey Prusa-Techies! You are going to miss a beer! And I bet it is at least as good as your local beer!

Cheers 

RE: XL firmware 6.4.0 alpha

@ElDudinero Are you saying that after the download you recalibrated and you seem to have no issues at all with this version? I loaded Alpha and had nothing but issues and skeptical on loading the released version with the posts on here?

RE: XL firmware 6.4.0 alpha

I had spectacular crashes with the alpha but I've been printing a fair bit with the release version now and everything has been fine. I did do a calibration after installing the final version. 

RE:

@Rufus

The Alpha was a PITA to work with having all those crashes.
The Release-Version works fine for several days now. Better, smoother and with all heads enabled.
After flashing, I cold-rebooted and recalibrated the x/y-Axis TWO times: First I tried the "Autohome" from the "Control" Menue. That produced really hard bumps at the front left corner. So I recalibrated X/Y-Axes from the "Calibrations and Tests" from the "Control" Menue. Then I calibrated the toolheads with the pin screwed in the hotbead. - Since then I have no issues. (knock on wood)

Maybe it would make more sense to calibrate them first, an then autohome? - I guess it should autohome without the bumping sound...

RE:

That's not what I'm saying: I'm saying, the "stable" release crashed one tool into another after I 

- flashed the latest stable release  (v6.4.0)
- Factory-reseted
- restarted the printer (I always do a hard reset after a firmware update, in case the memory has not been cleaned up properly);
- Calibration wizard (you know, Prusa  winking at us; I wonder why!) - everything went alright;
- took tool #1 out to clean the nozzle, then tried to park it... and that's when it went berserk and crashed into tool #2, knocking it out of its dock. A full red screen with an error message welcomed me. 😉 

Posted by: @rufus

@ElDudinero Are you saying that after the download you recalibrated and you seem to have no issues at all with this version? I loaded Alpha and had nothing but issues and skeptical on loading the released version with the posts on here?

RE: XL firmware 6.4.0 alpha

For calibration purposes, it doesn't matter what slicer version you use.

Yes, I did re-calibration and factory resetting. Please read my reply to Rufus.

No, there was no problem during calibration. The crashes took place after restarting, the 2nd crash when trying to calibrate the IS. (The 2nd crash took place after turning off, then on the printer subsequent to the first crash.)

Cheers

Posted by: @eldudinero

Interesting. 

What Version of Prusa-Slicer are you running on? - I run the newest version without any entry or exitcodes.

Did you a restart/ xycalib/ Toolheadcalibration?

Did the sledge loudly bump into the front/left block during calibration? 

Cheers 

RE: XL firmware 6.4.0 alpha

I have finished calibrating my 5 Head XL - after flashing 6.4.0+11974.   I noticed some big changes in the way the filament loading and unloading happens, which I think are improvements.  The filament is not left in the hot end when loading, it is extruded and when OK it retracts.

I think this will help the problem I have been having of regular jams in the Nextruder.  Has anyone else had experience with this?

Also curious of other changes

RE: XL firmware 6.4.0 alpha

Just wanted to report my experience with 6.4.0 as when searching for solutions to my new issues, I see that a few others have had similar problems.

The XL has been rock solid since day one (Q4 2024) other than occasionally losing connection with Prusa Connect and needing a power cycle to reconnect. I've really never even watched it go through it's startup procedure or lay down a layer since the first week as it never fails.

I didn't use it for a few weeks as I was busy moving to a new house. Set it up in the new place, updated to the latest firmware when I fired it up, and tried to use it. It continually fails the Nozzle Cleaning and then fails the bed calibration if I ignore the nozzle cleaning. I'd never had this before, so fully cleaned the nozzle to shiny brass, but a tiny bit of oozing seems to always happen and it fails again unless i take a thin tool and reach in and get rid of the tiny ooze just as the nozzle cleaning cycle starts. 

I initially assumed that perhaps it wasn't happy having been moved, so re-ran all of the original calibrations, checked belt tightness, etc. Same issue. This is using Prusa PLA and PETG and happens on all 5 heads.

After the calibration, the machine is now the noisiest it's ever been and can be heard throughout the entire house. Re-calibrated a few more times, but it still sounds awful and fails on nozzle cleaning and bed levelling on every print due to the slight oozing and ineffective nozzle cleaning.

I'm going to give it a factory reset and flash back to 6.2.6 to see if that fixes the issues.

RE: XL firmware 6.4.0 alpha

Thanks for sharing your experience.  I also upgraded a few days ago and for me it seemed to solve a major problem,  I have had many, many filament jams in the nozzle.

I became very good at swapping the nozzle and heating - clearing the jammed one.  The new firmware tries to clear the hot end of filament when not printing.  After a swap it retracts the filament out of the hot end.   

I am having the same situation as you with the error the nozzle cleaning has failed.   I have never had this error in the 2+ years of using my XL.

Prusa should go into more depth of what firmware changes are made in the new releases and what they are supposed to fix or improve.  This latest seems to have many and it is not obvious why or what

RE: XL firmware 6.4.0 alpha

I upgraded from 6.2.2 to 6.4.0 today and immediately experienced an auto home crash in the front left corner. Printer was working fine until the firmware update. Tried auto homing through the calibration menu on the LCD several times, including after power cycle and moving the carriage to the center of the print bed manually. After homing in the front left corner it seems to skip violently while moving out of the corner.

Once I reverted to 6.2.2 auto home immediately completed without issue. I don't think I damaged anything (fingers crossed) but will keep an eye on it.

6.4.0+11974: Reproducible tool-parking collision (T1 veers into T2 dock) triggered by P0 S1 in End G-code

Hi Prusa team / XL owners,

I want to add a detailed, reproducible case of the same class of tool-parking crash described earlier in this thread (tool veers sideways during “park tool” and hits the neighboring dock). I can reproduce it reliably at the end of a print and it already happened on two identical prints, so this does not look like a one-off.

Summary

During End G-code, the printer executes P0 S1 ; park tool.

Instead of parking Tool 1 cleanly, Tool 1 drives into / collides with the tool dock area near Tool 2 (sideways deviation / wrong path).

Collision is fully reproducible with the same BGCODE on my machine.

Environment

Printer: Original Prusa XL (tool changer; at least Tools 1 and 2 installed) -Printer bought November 2025

Firmware: 6.4.0+11974

Bootloader: 2.5.0

Buddyboard: 9.0

Slicer: PrusaSlicer 2.9.4

File type: .bgcode (sent/printed from USB)

What I expected

After the print finishes, End G-code should park the currently mounted tool safely (or at minimum never drive into a neighboring dock).

What happens instead (actual)

At the end of the print, when the End G-code reaches the park command, Tool 1 moves toward the tool docks but then veers into the area close to Tool 2 and collides with the tool storage/dock. It happens fast and is not recoverable without intervention.

Repro steps

Flash/Run FW 6.4.0+11974.

Slice with PrusaSlicer 2.9.4 using standard XL profile.

Print the attached large part (single-tool print).

Let the print complete normally.

Observe the printer executing End G-code. When it reaches P0 S1, Tool 1 collides near Tool 2.

End G-code snippet (from PrusaSlicer)

This is the relevant part (note that P0 S1 is unconditional):

G4 ; wait
{if layer_z < max_print_height}G1 Z{z_offset+min(max_layer_z+5, max_print_height)}{endif} ; Move bed down
P0 S1 ; park tool
{if layer_z < max_print_height}G1 Z{z_offset+min(max_layer_z+97, max_print_height)} F300{endif} ; Move bed further down
...
M84 ; disable motors

The crash is reproducible with the same BGCODE.

It occurs exactly when the firmware executes the park-tool routine (triggered by P0 S1).

The print itself completes fine; the failure is in the final tool-parking motion.

This matches reports in this thread where parking Tool #1 causes it to veer and crash into Tool #2.

Workaround (confirmed)

If I remove/disable P0 S1 in End G-code, the print finishes without attempting to park and the collision does not happen. Obviously not ideal, but it prevents damage.

What I already did / checked

The issue occurs after printing a large part (long print). I can reproduce on demand.

I can provide:

the exact .bgcode

the .3mf

video of the final parking move

crash/error screen photo if it triggers one

printer log / support bundle (please tell me the preferred way to export for XL)

Request to Prusa devs

Could you please investigate the P0 S1 park-tool routine in 6.4.0+11974 for XL tool changer, specifically:

why the tool sometimes deviates laterally toward a neighboring dock during park,

whether a coordinate transform / docking path selection can become inconsistent after a print,

and whether this is linked to calibration state, homing method, or end-of-print state machine.

This is a safety issue (risk of damaging docks/tools) and it’s still present in the “stable” 6.4.0 release.

If you tell me exactly which logs/diagnostics you need (and where to find them on XL), I’ll attach them.

Thanks.

It's hard to judge from your picture but - are those docks a fraction out of line?

Show us the row of docks from the side so we can more easily see whether one is out of place.

Cheerio,

RE: XL firmware 6.4.0 alpha

Posted by: @diem

It's hard to judge from your picture but - are those docks a fraction out of line?

Show us the row of docks from the side so we can more easily see whether one is out of place.

Cheerio,

IMO, the question is moot: if the docks are “a fraction out of line”, that condition would potentially misalign the tool (toolchanger)  with the dock… maybe resulting in the tool not docking. It will not crash a tool into another tool, which is the result of moving the toolchanger sideways from where it was supposed to go. It’s simply mechanics, one doesn’t need a picture to understand the anomaly.

What @IPR reported is an identical situation to what was reported in another post, and confirmed as a bug by simply downgrading to the previously-stable release (6.2.6). And, yes, Prusa customer service is aware of this bug. According to the emails exchanged with them, the devs work on it for the next stable release. What makes it difficult to contain the problem is that this bug doesn’t affect the majority of XL printers - many users don’t experience the issue upon upgrading.

RE: XL firmware 6.4.0 alpha

And, yes, Prusa customer service is aware of this bug. According to the emails exchanged with them, the devs work on it for the next stable release. What makes it difficult to contain the problem is that this bug doesn’t affect the majority of XL printers - many users don’t experience the issue upon upgrading.

 

That sounds good. I'm very curious to see whether the next release will address the main points of customer complaints.

RE: XL firmware 6.4.0 alpha

Prusa has officialized the last 6.4.0 firmware

is anybody can give us some feedback? 

is the printer remain silent ?

is the head doesn't crash? 

after my multiple problems with the first 6.4.0 i 'm not in confidence....

RE: XL firmware 6.4.0 alpha

Prusa has officialized the last 6.4.0 firmware

is anybody can give us some feedback? 

See   https://forum.prusa3d.com/forum/original-prusa-xl-tool-changer-general-discussion-announcements-and-releases/as-of-6-4-0-the-xl-still-crashes-toolheads-into-one-another-it-is-inexcusable/paged/2/#post-779089

Some people are still seeing issues even though for me it's been working like a boss after installing the final version and recalibrating the toolhead offset