Error opening sound device.

[steve]

I'm running out of ideas. I can't reproduce the problem (on Big Sur with Audacity 2.4.2), and I don't see any reason for the error.

Try "Reset Configuration" (in the "Tools" menu), and then reboot your computer.
Any change?

[Joshua5684]

No change. I even reinstalled Audacity.

[steve]

Have you tried recording from the mic with Garage Band?
If not, please try that and let us know what happens.

[Joshua5684]

Yup, GarageBand works.

[steve]

My guess is that there's a "security" or "privacy" setting somewhere in the Big Sur settings that are preventing Audacity from playing. However, you appear to have already gone through all the security and privacy settings that I know of - perhaps Apple have added a new one that I don't know about.

What model is the Mac?

Unless a Mac expert comes along with the answer, I think you're going to have to use Garage Band or some other app rather than Audacity on that machine.

[Joshua5684]

My Mac is a late 2013 MacBook Pro. I don't think that's relevant, though, because I've used Audacity before (on previous versions of MacOS) and it was fine.
However, regarding security settings, Audacity doesn't come up as an app that has access to my microphone, but it's not that the box is unchecked; it's just not in the list.

[ferropop]

Having the exact same issue.

Exactly the same behaviour with TeamSpeak 3 since updating.

Neither of them present themselves as requesting microphone access in the privacy/security screens, so there's nothing to check, and there's no + button to manually add them either.

[steve]

Is you macOS up to date? The fixes that I can find on Google all say to update macOS.

[billw58]

Try moving Audacity from the Applications folder somewhere else, such as the Downloads folder. Then start Audacity, click the Record button, and see if you are requested to give Audacity permission to use the "microphone". Quit Audacity and move it back to the Applications folder.

-- Bill