Cannot use USB port; it is being used by another application.


My Cubase Pro 9,5 will not work with my UR44.
When I start Cubase Pro 9,5 The dspMixFix UR44 shuts down and gives
the following message : Cannot use USB port; it is being used by another application.
With Cubase SX 3 the UR44 works correctly.

What must I do to fix this ?

Whit kind regards,
Marcel Kemp

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Hi and welcome,

Make sure you have the very latest driver and TOOLS installed, please.

Read about the Cubase integration in UR manual.

Hi Martin and Grim,

First of all thanks for your respons.
very appreciated.

Latest Driver and tools are installed.
( no success )

1- re-instal Windows 10
2- re-instal Cubase Pro
3- re-instal UR 44 ( included latest drivers )
( no success )

regedit HKEY_LOCAL_MACHINE - SYSTEM - CurrentControlSet -Services USBSTOR - Value 3-4.
( no success )

Disable USB Ports from Device Manager
and re-start
( no success )

I’m afraid that the problem must be somewhere
in the software of Cubase pro or in the software of the UR 44
Cause under Cubase SX3 the UR 44 works correctly.
Cubase Pro recoginizes the UR 44.
but still it gives me the message:
Cannot use USB port; it is being used by another application.

Grim: I will read the UR manual again to find a solution for
my problem. :smiley:


Definitely it’s strange you cannot install the latest driver. Why? Any message?

Could you try to restart your system and start Cubase Pro immediately (as the very first application)? Could you check what applications are running in the background?

Did the actual driver installation fail or with ‘no success’ you mean that the message about the USB Port being used is still there?

If it’s the latter, Grim pointed you in the right direction - the message is due to the hardware integration in Cubase: when Cubase is running, you can access the UR44 options from the Audio Hardware Setup in Studio Setup (formerly Device Setup) and DspMixFx is not accessible.

You don’t see this behaviour in SX 3 because there was no hardware integration (the whole UR series is much newer than SX 3).

Kind regards,

Yes and it’s sad that dspMixFx can’t be operated “from” Cubase or can’t be running simultaneously…
It is so much more convenient than control room + cues…

I wonder if KempCubase ever got an answer to his question. I’m getting exactly the same message. “Cannot use USB port; it is being used by another application.” I’m running a new version of Cubase Artist 9.5, and I’ve installed the latest version of “Tools for UR44” including the latest drivers. Yet every time I open this dspmixfx software I get the same message and Cubase stops working. Can anyone advise, please?


You can’t use dspMixFx when Cubase is using the driver. Cubase takes over the control over the driver. This is by design.

Look at screenshot where to find dspMixFx functionality inside Cubase. Don’t forget to add the inputs first (f4\input tab)

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It is not just problem using Cubase and dspMixFx at the same time because it can’t work. Problem is deeper.

  1. dspMixFx closed, opening Cubase leads to crash it if you choose UR(242 in my case) driver.
  2. If you open Cubase with some different drivers it wirks fine, but when you want to change drivers to UR drivers, Cubase crashes
  3. When Cubase is closed and you want to use dspMixFx standalone, opening it it shows that UR is missing and after few seconds comes message “Cannot use USB port…”
    For information, UR is connected directly. I am not using any USB hub.
    MacMini, Sierra…


Make sure the latest UR242 driver, Tools and Firmware is installed. I would also recommend to try to use different USB cable, and USB port. For me it seems to be on HW side.

I am looking at buying the UR28M but this thread seems to be saying that you cannot use the DSP effects if cubase is running, so how would i be able to add comfort reverb to a vocal during takes please?


You can use the DSP effects if Cubase is running. You control the DSP from Cubase then. You can decide, if you want to use the plug-ins as common VST (so they are processed on the CPU) or if you want to process then on the Audio Device’s DSP.

having same problem with my UR 242 and Cubase AI8

I’m getting same message with a Mac. UR44 dspMixFx"cannot use USB port". This is when I try to load it without Cubase or any other DAW being open. Is it just crap software?