6.4.1 Beta Firmware for the Prusa XL - General discussion, announcements and releases

RE: 6.4.1 Beta Firmware for the Prusa XL

dsolana — Fri, 10 Apr 2026 05:23:41 +0000

After upgrading from firmware version 6.2.5 to 6.4.1-RC during the new calibration steps, the toolhead crashes with the filament sensor calibration tests.

RE: 6.4.1 Beta Firmware for the Prusa XL

bsw — Wed, 25 Mar 2026 00:10:10 +0000

My 5T XL seemed to work O.K. with 6.4.0 I had a couple tool crashes but detaching prints seemed to be the cause. I switched to the 6.4.1. Beta and everything seems fine so far, my only issue is when I run the input shaper calibration it complains that the frequencies are too low (X and Y) and I need to tighten the belts. Howeve my gantry is square and my belt frquecies are 88/91 which the Betlt tuner says in slightly high. I ran a Homing tower to verify and it was flawless. I tightened the belts so more to see if it helped but no workee.... Still need to maybe w=switch back to 6.4.0 or 6.2.6 to see if input shaper works.

RE: 6.4.1 Beta Firmware for the Prusa XL

dmbgo — Mon, 16 Mar 2026 05:08:08 +0000

I second that BullDog8484. My 5T xl is working well with this beta version. Previously, if I didn't remember to clean the print head b4 starting a print, it would always say printhead cleaning failed.

RE: 6.4.1 Beta Firmware for the Prusa XL

BullDog8484 — Wed, 11 Mar 2026 23:31:19 +0000

A little over 100 hours of printing on 6.4.1 Beta. Multiple models, nearly 1500 tool changes. No issues at all. Print quality looks to be a little better. Maybe because of the phase stepping now working.... Maybe? Will continue testing, but very pleased so far.

RE: 6.4.1 Beta Firmware for the Prusa XL

ErikSimon — Sat, 07 Mar 2026 19:38:21 +0000

I installed it to try out, the printer is atleast not trying to break itself apart like on the 6.4.0. However it still won't even get passed the probing. Neither 6.4.0 or 6.4.1 is able to complete the probing. I've tried both dimonback nozzle, Obxidian, Prsua XL PA bed and Prusa xl Satin bed.

I'm going back to 6.2.6.

RE: 6.4.1 Beta Firmware for the Prusa XL

BullDog8484 — Sat, 07 Mar 2026 09:45:31 +0000

So, yeah, of my two XL's, one was completely stable on 6.4.0. The other had intermittent toolhead crash and homing issues. Rolling back to 6.2.6 fixed everything. But I'm now testing 6.4.1 on the problem machine and so far, it's rock solid, and quieter than 6.4.0 was. I'm not 100% confident, but I'll move to some small production runs to stress it. 6.2.6 is on hot standby just in case.

RE: 6.4.1 Beta Firmware for the Prusa XL

JavaBean — Fri, 06 Mar 2026 16:35:00 +0000

one of the problems with them admitting 6.4 was a problem is that many people had no issues with 6.4. i myself have done several multi-day, multi-tool prints on 2 different xl's both running the 6.4 release. at this time i have no reason to revert, 6.4 is stable for me. and many others as well

RE: 6.4.1 Beta Firmware for the Prusa XL

mgantner — Fri, 06 Mar 2026 14:57:36 +0000

6.4 cost me a lot of filament and many multiday print failures. I've lost confidence. I think I'll just remain one release firmware behind at all times. Took way too long to admit 6.4 was a problem.

RE: 6.4.1 Beta Firmware for the Prusa XL

adesir — Fri, 06 Mar 2026 14:26:12 +0000

https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/5147

RE: 6.4.1 Beta Firmware for the Prusa XL

Nagoya kogei — Fri, 06 Mar 2026 09:42:14 +0000

Hi, I updated from 6.2.6 to this beta version, but I'm getting an error during phase-step calibration.

The first problem is that if you run phase-step calibration alone, it will start operation without picking up a tool.

Until now, the tool would always be picked up and calibration would start.

I have confirmed that if I run phase-step calibration with tool (T1) attached, it completes successfully without any errors.

Please check that it works properly.