So you are turning on the module first then booting up the PC? That is backwards. Normally you turn on the PC first, then go down your chain turning on each thing in order. It's quite normal for MIDI devices to send random bits of junk data when they boot up. For example I start up my PC, then power on my UW500, and lastly my MU2000. That is how a MIDI chain is meant to work. Either way though, you can just use the buttons on the Module to reset the unit after the junk data is received. I'd bet the X3MB is also getting the junk data, it just isn't reporting it you as it doesn't have a screen. In general most modules will just ignore data it doesn't understand, but Yamaha modules from the MU line will report it. Even with the Illegal Data message displayed, the module will still accept incoming MIDI and play everything it understands just fine.

The weird part is that regardless of my button pushes error message doesn't go away. It shortly flickers normal screen and then message is back.
At first I thought that card keeps sending junk, but even when I shut my PC down message stays. Only MU50 cold power cycle helps.
Also unit doesn't play anything. From PC side however it looks like it's playing fine.

Actually I don't think there is software solution from software/conf side since as soon as I start PC even before any op.system driver loads MU50 fails with this mssage.
One of the workarounds of course is to use 2nd YMF718-S sound card and disable game port on my AOpen card.

Update: It turns out that all my PCI sound cards are giving me that error. I tested it with Aureal Vortex 2 card. I even tested it on my Core 2 Quad rig - same result.

All ISA cards are working just fine. Weird...

I have a MU50 connected to various systems behind an Edirol UM-550 patchbay. Same illegal data here. Possibly it correlates to doing stuff with my MT-32 (connected behind same patchbay), so in my case it might indicate SysEx commands outside of GM (or XG). In any event I'm seeing it right now, on ISA too (AudioExcel AV310 card, with CMI8330 chipset). I see it on other ISA cards too, then again, it's the UM-550 it's directly connected to.

Edit:
Been playing around with my setup and the "illegal data" error only seems to occur if I'm lazy and have both MT-32 and MU50 patched in at the same time and I play some MT-32 game.

vutt wrote on 2019-10-14, 09:07:

Hi! […]
Show full quote

Hi!

I'm getting following error on my Yamaha MU50 as soon as I power on my PC with AOpen AW744-II PCI sound card on i440BX system.
mu50.jpg
It looks like erroneous midi data from sound card causes this according to manual.

To make it more confusing my MU50 works fine with my other YMF718-S based ISA card.
Also AOpen AW744-II works fine with my other external sound module (Serdaco X3MB).

Any ideas how to troubleshoot this?

Did you ever get anywhere with this? I'm having this exact issue with an ESS audio drive ISA card on a gigabyte ga-6vxc7-4x mobo. Worked fine until I moved my PC. I have 2 audiodrive ISA cards an ES1869F and an ES1869FC and it does it with both. I'm stumped. I ordered a new cable. Perhaps I'll try it with my yamaha YMF724 PCI card.
EDIT: I have a Yamaha MU-90

What's the exact timing of the message?

For example - Does "Illegal Data" show on the module's screen immediately after the PC is switched on? Before the PC has even completed it's POST sequence?

And, does the message then disappear at a particular moment?

It would be interesting to do a detailed monitoring of the (soundcard's MIDI- or game-) port as the incident happens, see exactly what signals are coming through it.

It happens as soon as I power on the PC when plugged into the gameport. I have tested my MU90 with a USB MIDI cable in Windows XP on the same machine and it works fine...I may have stumbled upon a solution, though. If I unplug the MIDI out cable from the MU90 it seems to work. I also disassembled the unit and reseated everything.

Clkish1988 wrote on 2021-08-02, 11:32:

It happens as soon as I power on the PC when plugged into the gameport. I have tested my MU90 with a USB MIDI cable in Windows XP on the same machine and it works fine...I may have stumbled upon a solution, though. If I unplug the MIDI out cable from the MU90 it seems to work. I also disassembled the unit and reseated everything.

Or you could first turn on the PC, and then turn on the MIDI module, as SuperDeadite already suggested earlier in the thread...

yawetaG wrote on 2021-08-02, 15:08:

Clkish1988 wrote on 2021-08-02, 11:32:

It happens as soon as I power on the PC when plugged into the gameport. I have tested my MU90 with a USB MIDI cable in Windows XP on the same machine and it works fine...I may have stumbled upon a solution, though. If I unplug the MIDI out cable from the MU90 it seems to work. I also disassembled the unit and reseated everything.

Or you could first turn on the PC, and then turn on the MIDI module, as SuperDeadite already suggested earlier in the thread...

Already tried this long before I posted to this thread, and I still get "illegal data" message ...thanks though

Also, kinda don't appreciate the condescension...people come to these forums for help...I do read entire threads and try solutions listed before asking any new questions...thanks again

Clkish1988 wrote on 2021-08-03, 15:11:

yawetaG wrote on 2021-08-02, 15:08:

Clkish1988 wrote on 2021-08-02, 11:32:

It happens as soon as I power on the PC when plugged into the gameport. I have tested my MU90 with a USB MIDI cable in Windows XP on the same machine and it works fine...I may have stumbled upon a solution, though. If I unplug the MIDI out cable from the MU90 it seems to work. I also disassembled the unit and reseated everything.

Or you could first turn on the PC, and then turn on the MIDI module, as SuperDeadite already suggested earlier in the thread...

Already tried this long before I posted to this thread, and I still get "illegal data" message ...thanks though

Also, kinda don't appreciate the condescension...people come to these forums for help...I do read entire threads and try solutions listed before asking any new questions...thanks again

Sorry, but you did not mention you tried the proposed solutions already. I cannot read your mind.

Anyway, since the illegal data message means the MU is receiving nonsense data, have you tried turning on your PC first, waiting until it has fully booted, and then turning on the module?

...well 3 years later I found workaround to fix for my problem.

I bought recently one more midi module - Roland SC55K.
Tested two daisy-chained configurations:
1. PCI card gameport out -> MU50 -> midi passthrough -> SC-55K = "illegal data" on MU50 screen and both modules INOP
2. PCI card gameport out -> SC-55K -> midi passthrough -> MU50 = Both modules working as intended 😀