When Hazel Rules Stop Running on External Drives — The Metadata Indexing Fix That Got Workflow Automation Working Again

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Ah, Hazel. The tiny but mighty automation tool for macOS users who love things tidy and well-organized. One day, your files are flying into neat folders, renaming themselves, and disappearing into the correct archive. The next? Nothing. Especially when working with external drives. If your Hazel rules have mysteriously stopped doing their job on your trusty SSD or external hard drive—you’re not alone. I was there too. And I found the fix.

TL;DR

If Hazel suddenly stops working on external drives, it’s likely due to metadata indexing being turned off. Hazel relies on macOS’s Spotlight indexing system to detect file changes. Without it, Hazel thinks nothing has changed—and does nothing. Turning on Spotlight indexing for your drive brings Hazel back to life, working its automation magic once more.

Setting the Scene—When Hazel Goes Silent

If you’ve used Hazel, you know it’s a genius at automating file management—renaming, organizing, trashing, even running scripts. It watches folders, waits silently, then bam!—action. So, when Hazel suddenly goes silent and rules stop applying to files on your external drives, it’s frustrating. Especially if the same rules work flawlessly on your Mac’s internal drive.

I was scratching my head. My rules were simple: move files, rename them, sort them into folders by date. They worked before. What changed?

The Clues Were There—Hazel Needs Spotlight

Hazel doesn’t just randomly scan folders; it listens. It waits for updates. It relies heavily on macOS metadata listeners, and these rely on Spotlight indexing. If Spotlight indexing is turned off on a drive—by user choice or accident—Hazel becomes clueless. It simply won’t see any file change activity.

This means no rules get triggered. Hazel waits for a signal… that never comes.

How to Check If Indexing is Disabled

It turns out, macOS will sometimes disable Spotlight automatically on certain external drives. Or it may have been added to the “do not index” list.

Here’s how to find out if that’s the case:

  • Open System Settings (or Spotlight Preferences depending on your macOS version).
  • Look for the Privacy tab in Spotlight settings.
  • See if your external drive is listed there. If it is—aha! That’s the issue.

Drives listed here are excluded from indexing. Hazel won’t see updates on them.

Removing the Drive from the No-Index List

This part is easy:

  1. Select the drive in Spotlight’s Privacy tab.
  2. Click the small “-” (remove) button.
  3. Close Settings. macOS will start indexing the drive again.

But wait… you’re not done just yet.

Force a Reindex with Terminal (If Needed)

Sometimes, removing a drive from the exclusion list doesn’t kick off indexing right away. That’s when Terminal comes in handy. Don’t worry—it’s just one simple command.

Open the Terminal app and type:

sudo mdutil -i on /Volumes/YourDriveName

Replace YourDriveName with the actual name of your external drive. You’ll probably be asked for your admin password. Enter it and hit return.

If indexing starts, you’ll see a message like:

/Volumes/YourDriveName: Indexing enabled.

If it was already on, you might see:

/Volumes/YourDriveName: Indexing already enabled.

Check Spotlight is Actually Indexing It

Here’s a trick: open Spotlight (using Command + Space) and search for a file you know is on the external drive. If results show up—boom! Spotlight is running. If not… give it time. Indexing might still be ramping up, especially on large or old drives.

Hazel should soon be back in business, waiting for file changes and working its magic.

What If Spotlight Indexing is Still Disabled?

Sometimes macOS is stubborn. You might try everything, and indexing still won’t stay on. In that case, try:

  • Reformatting the drive: Use APFS or Mac OS Extended (Journaled). Some formats aren’t Spotlight-friendly.
  • Checking drive permissions: Ensure your user account has read/write access.
  • Running Disk Utility’s First Aid: A corrupted drive might not index correctly.

If all else fails, there’s a last-ditch method…

The Nuclear Option: Delete and Rebuild the Index

You can nuke the old index and force macOS to rebuild it. Again, go to Terminal and type:

sudo mdutil -E /Volumes/YourDriveName

This deletes the Spotlight index. macOS will then rebuild it from scratch. Hazel will jump back into action once it recognizes the changes.

Bonus Tip: Use Smart Hazel Rules for External Drives

Now that your Hazel rules are working again, here are a few best practices when dealing with external drives:

  • Use precise conditions — External drives can have many files. Don’t overwork Hazel by applying generic rules.
  • Enable debug logging — If Hazel seems off, turn on logging to help diagnose issues.
  • Test new rules locally first — Once they work, apply them safely to your external volumes.

Final Thoughts — When Tech Breaks, We Troubleshoot

This problem had me stumped for hours. Google searches didn’t help. Rebuilding rules didn’t help. But knowing that Hazel depends on Spotlight indexing was the lightbulb moment. Once indexing was turned back on, my folders zoomed back into automation bliss.

Technology breaks. That’s okay. What matters is being curious enough to poke around until something clicks.

A Quick Summary of the Fix

  • If Hazel isn’t working on your external drive, it’s likely due to Spotlight indexing being disabled.
  • Go to Spotlight’s settings and check the Privacy tab.
  • Remove the drive from that list, or re-enable it using Terminal.
  • Rebuild the Spotlight index if needed.

Once Spotlight sees your files again—Hazel does too. That means your automations will be up and running exactly the way they should.

Back in control. Back to effortless organization. Hazel would approve.