[BUG] 3.12.0-BETA1 + MMU2S - printer is stuck on MMU2S failure - it does not react to MMU2S buttons or recovery (e.g., loading filament)

[RPospisil]

Printer type -MK3S+
Printer firmware version - 3.12.0-BETA1

MMU upgrade - MMU2S
MMU upgrade firmware version - 1.0.6

USB/Octoprint

Describe the bug
When MMU2S is in failure state (e.g., filamant is not loaded, or out-of-filament), then printer displays error message containing like "press button on MMU unit to continue". Anyway pressing any button on MMU2S unit or recovering the MMU2S failure (by loading the filament) is not read out by printer and printer is stuck forever, so only possible solution is to reset it.

To Reproduce
Use printer menu to load filament but do not insert the filament to MMU2S. After a while printer displays error message and it is not possible to recover printer by loading the filament (using MMU2S buttons). Printer is stuck and the only solution is to reset printer.

Expected behavior
When MMU2S failure is resolved (e.g., by loading the filament using MMU2S buttons) printer shall continue.

G-code
N/A

Video
NONE

[ursius2020]

I can confirm and also found out this problem is present since v3.10
Also talked with the Support about this…
I hope this issue will be resolved soon or with v3.13 when also the MMU firmware is reworked

[E-Extrude]

Another confirmation.
Fully stock MK3S and MMU2S.
Once MMU issue is resolved the MMU responds to the buttons as if it isn't mid print and the main knob on the printer just cycles the MMU error message. No option but to reset printer and scrap print :(

[Prusa-Support]

Thanks for bringing this to our attention.
Have you actually tried resetting the MM-control board by pressing the embedded button?
Use a hex key to reach it from the right side, it can be found next to the micro-USB port. At that point, the Multi Material should reboot and resume the previous operation, without losing the print progress.

Michele Moramarco
Prusa Research

[E-Extrude]

When the MMU reset button is pushed, the unit homes the idler and selector barrel (unsure on correct term) and a green light appears above the filament selected. Just as you would hope, all errors have been cleared and the MMU is now ready. But the message isn't getting to the printer to resume printing.
Thanks for your time looking into this.

[RPospisil]

I've re-tested the issue again on 3.12.0-RC1 and it is still there. AFAIR the last version where it worked was 3.9.x .

@Prusa-Support I've tried to reset the MMU2S unit as you suggested - it did not help (personally I did not believe that it is linked with the issue).

[Prusa-Support]

Thank you for clarifying.
If I understand correctly the problem is a missing option on the User Interface to resume the print in this specific scenario. Probably this is not only a bug but a UI Feature Request.

Our developers will look into this.

Michele Moramarco
Prusa Research

[RPospisil]

Hi,
IMO it is defect/bug. It is not feature request because it worked before (AFAIR ~3.9.x). For example (see previous posts) during the failed filament loading (executed from the printer menu "load filament") following errors are displayed on the printer:

#~ msgid "MMU needs user attention."
#~ msgstr "MMU potrebuje zasah uzivatele."

#~ msgid "Fix the issue and then press button on MMU unit."
#~ msgstr "Opravte chybu a pote stisknete tlacitko na jednotce MMU."

In the past once I loaded the filament using MMU2S buttons, the printer read the status from the MMU2S and continued. In the current firmware I have to do reset of the printer.

Further the communication between MMU2S and printer is broken and for example a simple recoverable failure (such as failed loading the filament on filament switch) ends with necessity of the printer reset (but it worked in past)...

[Hauzman]

I can confirm to when the MMU is not working also on the 3.12.0-RC1. same think on my MK3S+

[Mirarkitty]

Can confirm. Issue in beta1 and rc 1 for me. Hoping for resolution before release... I would consider it a blocker for release since MMU2 with any problem will break the print as it is now.

[gudnimg]

Can anyone confirm which firmware this issue first appears in? 3.10.0? 3.10.1?

It seems like this issue isnt new with 3.12.

If this issue has been present for more almost 2 years, I wouldnt be surprised if Prusa Research decides to focus on 3.13 instead. Currently this isnt an issue with the upcoming MMU FW.

[ursius2020]

The Problem started with 3.11

Starting with 3.10.0 OctoPrint PSUControl is no longer turning off the PSU after the print is finished and cooled down. So i am now using 3.9.3 until 3.13 comes out and hopefully all issues have beed resolved