From Microsoft Forum related to MMDevApi.dll:

1. Find CMD in the search bar, open the command prompt (run as administrator), then type the following command and press Enter:
   regsvr32 /u MMDevApi.dll regsvr32 MMDevApi.dll

This will re-register this DLL file and can sometimes resolve the crash.

What internal audio device are you using, did you update those too like Realtek for your motherboard?
As I read it seems like you are using FlexASIO... could uninstall that for now? (restart PC)
Open Command Prompt again as Admin and do these stages one by one waiting each time until that stage finishes:
dism /Online /Cleanup-Image /CheckHealth
(wait till finished)
dism /online /cleanup-image /restorehealth
(wait till finished)
sfc /scannow
(wait till finished)

Also you could try changing these in Advanced [Tab] with the blue ticks to the opposite and Apply
both for Playback and Recording:

 

Last edited: Sep 23, 2025 at 8:54 PM

Not just for Cubase employees... it is very useful for Cubase users too and can help eliminate VST/VSTi plugins that are causing crashes as well as other things

 

I get an access denied error when I type this in an admin CMD tab, so I may have to unlock permissions somewhere first

Did the other prompts as well, and restoreheatlh did say that that something was fixed and scannow didn't detect anything out of the ordinary either. Also uninstalled Flexasio and tried to replicate a cubsae crash be activating and or disabling the interface and it still crashed. For reference I also did the same on FL studio 24 and it didn't even flinched.

Opening the volume settings menu from the taskbar in windows is also crash prompt now

 

Last edited: Sep 24, 2025 at 7:05 PM

Back up your user data and reinstall Windows!

 

Yes, that's my reading too. I'm guessing software (not just Cubase) is trying to list (enumerate) your audio devices and their properties and at least one of your devices disappears (or advertises a property that doesn't exist) the moment it's being queried, causing a crash. Can you scale down to just your interface and the most recent stable driver? No virtual cables, no ASIO, no additional devices, nothing else at all, just one in, one out?

 

Probably best to backup now and reinstall Windows or you could even try a Repair Install and Keep your Files/Installed Apps etc. and see if that fixes the issue.
Or before that create a new User Account (Profile) as Admin and see if the issue still exists.
Good luck!

 

Last edited: Sep 24, 2025 at 10:33 PM