Rescanning Sonnox AU Plugins in Logic Pro

Modified on Tue, 16 Sep at 4:29 PM

If your Sonnox plug‑ins are not appearing in Logic Pro, you may need to rescan them so they pass Apple’s AU validation process.

This guide covers the recommended in‑DAW rescan method for modern macOS systems, as well as the manual Audio Unit cache reset for older Logic versions.

Prerequisites

Latest Sonnox plug‑in installers (download here).
Latest iLok License Manager installed and licences activated.
Logic Pro fully closed before any manual file changes.

Step‑by‑Step Solution

1. Rescan from Logic Pro (Recommended)

Open Logic Pro.
Go to: Logic Pro → Settings → Plug‑In Manager
(Older versions: Preferences → Plug‑In Manager).
In the Manufacturer column, select Sonnox.
Look for unavailable plug‑ins — these will have the Use checkbox unticked.
Select the unavailable plug‑ins, then click Reset & Rescan Selection (bottom right).
Logic will run the AU Validation scan.
- If successful, the plug‑ins will now be available.
- If they fail validation, see [Why Doesn’t My Plug‑in Show Up in My DAW?].

2. Perform a Full Audio Unit Reset (If Needed)

If individual rescans don’t work:

In Plug‑In Manager, click Full Audio Unit Reset (bottom left).
Quit and restart Logic Pro.
The DAW will re‑validate all installed AU plug‑ins.

3. Manually Reset the AU Cache (Older macOS / Logic Versions)

For older Logic Pro versions (pre‑10.2) or persistent scan issues:

In Finder, choose Go → Go to Folder… and enter: ~/Library/Caches/
Delete:
- com.apple.audiounits.cache
- AudioUnitCache/com.apple.audiounits.cache
- AudioUnitCache/com.apple.audiounits.sandboxed.cache
Log out of your macOS user account, then log back in.
Re‑open Logic Pro — it will rebuild the cache and re‑validate AU plug‑ins.

Troubleshooting / Alternative Fixes

Still failing validation – Ensure your Sonnox plug‑ins are 64‑bit AU format (required since Logic Pro X) and fully up to date.
Licence issues – Check that your iLok activation is valid and on the correct machine/account.
Repeated validation failures – Some security/privacy settings in macOS may block new plug‑ins; allow them in System Settings → Privacy & Security.

FAQ / Common Questions

Q: Will resetting my AU cache delete presets or settings?
A: No, it only clears the scan cache. Your plug‑in settings remain unchanged.

Q: Why do my plug‑ins pass validation but still don’t appear?
A: Check that their category is enabled in Logic’s plug‑in manager, and confirm they are assigned to an instrument or effect slot.