VST3 "cannot be opened because the developer cannot be verfied"

This is a familiar scenario, which happens whenever opening a VST for the first time. However the usual solution is not working!

MacBook Pro 2014, Big Sur OS 11.6.8

The VST3 is Aeolus (organ emulator)

I go to System Preferences / Security & Privacy
I see the message “Aeolus.VST3” was blocked from use because it is not from an identified developer.
I click “Open Anyway”… but nothing happens.
Dorico’s error message won’t go away, even with repeated “Cancel”
Eventually Dorico launches, without the VST listed in the plug-in manager.

Is this Dorico? Or Aeolus? Or my computer?

FYI I’m having the same trouble opening the VST3 of Aeolus in Audacity. The Audio Unit version did open in Logic but it took several tries.

Probably, you might just want to disable Gatekeeper entirely:

sudo spctl --master-disable

In the terminal.

If this an old plugin that hasn’t been notarized through Apple’s nonsense servers, you will get these kinds of messages and/or the system will block the plugin from opening.

Should you disable Gatekeeper? I don’t know, but I do know Apple computers worked fine for 50 years without notarization requirements…

If the message is " Aeolus.VST3” was blocked from use because it is not from an identified developer.", then it is a problem of the plug-in and the vendor should fix it.

And switching off Gatekeeper is not a good idea, I think.
Because you simply turn off all security checks and not just the one for Aeolus.
Therefore, be careful…


No, you don’t want that at all.

These “nonsense” servers save people from installing dangerous “nonsense” software.


Of course they were connected to the Internet for the complete last 50 years. There are some small changes to the world since the first Apple computer.

If you don’t know what the Gatekeeper is good for you should not recommend people doing dangerous things.


The first thing you should do is to contact the developer of the VST, and ask them what needs to be done, either in terms of an update from them, or what you need to do.

You may be able to fix this by removing the quarantine flag from the files.

In a Terminal window, type:

sudo xattr -d com.apple.quarantine

followed by a space. Don’t press Return!

Then drag the plug-in onto the Terminal window. Now press Return.

You will asked to type in your admin user password.

I’d echo the comments here that disabling Gatekeeper is a very silly thing to do. It’s like removing your front door because you want to let someone in.


Thanks @benwiggy . I tried this and it did not work, even after a restart of OS.

I’ve submitted my issue to the Aeolus Github. Fingers crossed!

Perhaps one of you can help me with my confusion about VST file formats.

The Dorico manual says that 5.0.* uses VST 2. But I’ve never seen a .vst2 file extension. And I’m trying to squish a .vst3 into Dorico now. Is it just not going to work even if I get it past MacOS security?

There isn’t a .vst2 extension. VST2 plug-ins use .vst.

The VST3 plug-ins use .vst3, though.

Not sure what you mean. VST plug-ins should be installed into /Library/Audio/Plug-ins/VST3, and be available to Dorico when it launches.

Yes, but the current manual makes no mention of Dorico being able to use VST3

Is it possible you googled the manual and ended up with an early Dorico manual circa 2017? Dorico 5 definitely loads VST3 and you can white list VST2 if you need to. Get the current manual from the help menu inside Dorico.

I am in the current manual - just checked again.

OK now I see VST 3 mentioned on the page “VST and MIDI panel”.
However I was looking here (see photo) Does this mean that allowing/blocking is now only for VST 2 plug-ins? Thus VST 3 are automatic?

Related side note: it would be helpful if the web manual were searchable by phrases with quotes. In this case I needed to search for “VST 3” rather than VST3, but wasn’t able to.

Dorico did support VST3 plugs from the very beginning. In fact, we even drive the community of plug developers to drop VST2 support and to let Dorico’s audio engine only load VST3 plugs. Well, we have started this transition already by dropping VST2 on Apple Silicon. So VST2 is dead, long live VST3.
And yes, VST3 plug-ins are always detected automatically, you don’t need to whitelist them or anything.
But we also scan for VST3 plugs and do a quick short test with every plug-in. Should the test fail, the plug-in goes onto a blacklist and won’t get looked at anymore in the future. So if you are missing a plug-in on the list of available plug-ins and you that plug is VST3, then please create a diagnostics report and send to us.
Lastly, Dorico’s project file extension is *.dorico and into that project file go data chunks which represent the state of the plug-ins. At project close down Dorico collects those status data from every plug (actively used in the project) and at project loading time again, it distributes the data to the individual plugs. But this whole process is transparent for the user and all done automatically, so you will never see or deal with *.vst3 files.
Does that make sense to you?

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This all makes sense. Thanks @Ulf for the explanation.

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