Guide · macOS
Why macOS says your plug-in is “damaged,” and how to fix it
If a VST3, AU or VST suddenly shows “…is damaged and can't be opened”, the plug-in is almost certainly fine. It's the code signature macOS is rejecting, and that's fixable in seconds.
What the error actually means
Every app and plug-in on macOS carries a code signature, a cryptographic seal that tells the operating system the file hasn't been tampered with since it was built. macOS's security layer, Gatekeeper, checks that seal before it will load the code.
When you see “damaged and can't be opened” (or “can't be opened because Apple cannot check it for malicious software”), Gatekeeper has decided the seal is missing, broken, or untrusted. The plug-in's actual audio code is untouched. macOS just won't let it run until the signature is valid again.
Why it happens
- A macOS update. Security tightens with new releases, and signatures that used to pass can start failing.
- The quarantine flag. Anything downloaded from the internet or copied from another Mac gets an invisible
com.apple.quarantineattribute. On an unsigned or ad-hoc-signed plug-in, that triggers the block. - Moving your library. Copying plug-ins between machines, restoring from a backup, or migrating to a new Mac can invalidate the signature.
- An interrupted install. A copy that didn't finish cleanly can leave the signature inconsistent.
The manual fix (Terminal)
You can repair it yourself with two commands built into macOS. Replace the path with your plug-in's location (common folders are below).
First, strip the quarantine flag and other stale attributes:
sudo xattr -cr "/Library/Audio/Plug-Ins/VST3/YourPlugin.vst3"Then re-sign the plug-in so Gatekeeper accepts it again (this is an ad-hoc signature, with no developer certificate needed):
sudo codesign --force --deep --sign - "/Library/Audio/Plug-Ins/VST3/YourPlugin.vst3"Enter your Mac password when prompted, then relaunch your DAW.
Where plug-ins live on macOS
- VST3:
/Library/Audio/Plug-Ins/VST3/ - Audio Unit (AU):
/Library/Audio/Plug-Ins/Components/ - VST:
/Library/Audio/Plug-Ins/VST/ - AAX (Pro Tools):
/Library/Application Support/Avid/Audio/Plug-Ins/
codesign --verify --deep --strict --verbose=4 "…/YourPlugin.vst3". You want to see “valid on disk” and “satisfies its Designated Requirement.”Or fix it in one click
Typing sudo commands per plug-in is error-prone. One wrong path and nothing happens. Plugin Medic runs exactly these steps for you: drop the plug-in on the window, click Fix & Sign, done. It's free for one plug-in at a time.
Still won't load?
If the plug-in is signed and verified but your DAW still doesn't show it, fully quit and reopen the DAW so it re-scans, or trigger a manual plug-in rescan in its preferences. Some hosts cache a plug-in's “failed” state until you force a fresh validation.
If macOS still blocks the whole app (not a plug-in), see our guide on “Apple cannot check it for malicious software.”