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

All of a sudden DSPmix can no longer communicate with my UR824. I just get this message every time:

“Cannot use USB port; it is being used by another application.” -with the option only to click “Yes” in response.

I get this message even on a fresh startup with no other applications running (other than DSPmix).

I have the latest versions of the 824 firmware, and “TOOLS” installed, (as of today Sept 4).

Hope to hear some responses soon, as I was using DSPmix quite frequently up until now.

Is your UR824 plugged in the exact same port as it was when you installed the driver? If you change ports, you have to re-install the driver, it is port specific.
It must be a direct (on computer) port, Hubs won’t work properly.
Perhaps a re-install of the driver might be of help anyways.

This is really an annoying bug, also on Mac. Installed the drivers again. Than it went ok for a while. Now its back. Only restart helps. Looks like Steinberg forgot this piece of hardware.

They did not :slight_smile: UR824 and UR28M firmware and Tools update version 2 - UR Series - Steinberg Forums Lets see if this is fixed

Unfortunately this annoying bug or whatever is back. Only restart brings the UR28M back. In Cubase its working. Only the dspMixFx_UR28M app brings up this msg. A fix would ben nice.

Hi There

If you are using Cubase you do NOT use the dsp software, everything can be controlled from within Cubase itself, (which version are you using) so if you have the dspMIX running at the same time as Cubase, one of them will give this message

Beset Regards


Hi Dave,

thanks I know. Don´t use it together. It looks like that the driver is in some way blocked after a Cubase Session.


Sounds stupid, but this works. Mute UR28M, disconnect usb from computer, put it back, it should works now.

Thanks Srfjan, what a day saver, works.

I had this problem all the time with the ur824. Is it still a problem?

Years later, the issue is still there. Mac High Sierra, “Cannot use USB post; it is being used by another application”. Only restart can make it work again.


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