macOS Error -1008F: Fix Corrupt or Unsupported Apps

Quick Answer

If you're an advanced user, just run this in Terminal to clear the quarantine flag and retry:

xattr -dr com.apple.quarantine /path/to/app.app

Then double-click the app again. That fixes most cases.

What's Going On?

You saw the dreaded -1008F error when trying to open a downloaded app or installer. The message usually says something like "The operation couldn't be completed" or "This app is damaged and can't be opened." You might also see "You should move it to the Trash."

This error pops up when macOS's Gatekeeper — the security layer that checks app signatures — can't verify the app's code signature or sees that it's been tampered with. It happens most often after you download a program from a random website, not from the App Store. Sometimes the download itself gets corrupted mid-transfer, or the developer didn't sign the app properly.

The real culprit is often a hidden quarantine attribute that macOS attaches to every downloaded file. When Gatekeeper tries to validate that quarantined file, it fails and throws -1008F. The fix is to remove that attribute, or in more stubborn cases, disable Gatekeeper entirely for that specific app.

Step-by-Step Fix

Quit the app and any related processes.
If you see the error dialog, click "Move to Trash" or press Command+Q to close it. Don't worry, we'll recover the app later.
Locate the downloaded file.
Go to your Downloads folder (or wherever you saved it). If the dialog already moved it to Trash, open the Trash, right-click the app, and select Put Back.
Open Terminal.
You'll find it in Applications → Utilities, or just search for it with Spotlight (Command+Space).
Remove the quarantine attribute.
Type this command, but replace /path/to/app.app with the actual location. The easiest way is to drag the app icon into the Terminal window after typing xattr -cr (that's a space after -cr). The path fills in automatically.
```
xattr -cr /path/to/app.app
```
Hit Return. You won't see any output if it succeeds.
Try opening the app again.
Double-click the app in Finder. If it opens without the error, you're done. If you still get the error, move on to the next step.
Right-click and choose Open.
Instead of double-clicking, right-click (or Control-click) the app and select Open. macOS will show a confirmation dialog with an Open button. Click it. That sometimes bypasses the first-time warning.

If That Doesn't Work: The Gatekeeper Override

Sometimes the app's code signature is genuinely broken. The app might have been modified after download, or the developer didn't sign it properly. In that case, you have two options.

Option A: Temporarily Disable Gatekeeper

This is a broader fix. It opens your Mac to any unsigned app, so only do this temporarily and re-enable afterward.

Open Terminal.
Type this and press Return:
```
sudo spctl --master-disable
```
You'll be prompted for your admin password. Note that you won't see any characters as you type — that's normal.
Try opening the app. It should work now.
When you're done, re-enable Gatekeeper with:
```
sudo spctl --master-enable
```

Option B: Re-download the File

If the file got corrupted during download, the signature check will always fail. Delete the file completely, empty your Trash, then download it again from the official source. Make sure you use a stable internet connection — a flaky Wi-Fi signal can cause partial downloads that trigger -1008F.

Alternative Fixes That Sometimes Work

Check the app's security settings. Go to System Preferences → Security & Privacy. On the General tab, look for a message that says "[App name] was blocked from opening because it is not from an identified developer." If you see it, click Open Anyway.
Verify the app is actually for your Mac. If you downloaded a Windows version or a build for an older macOS, it won't run. Check the developer's website for compatibility.
Try a different browser to download. Safari sometimes adds extra quarantine checks. Chrome or Firefox might skip those.

Prevention Tips

Always download software from the official developer site or the Mac App Store. Third-party mirror sites often have tampered or outdated files.
After download, right-click the file and select Open the first time you run it. That tells Gatekeeper to let it through without the full quarantine check.
If you regularly download unsigned apps, consider adding the developer to your allowed list in System Preferences → Security & Privacy — that's safer than disabling Gatekeeper globally.

Error -1008F is annoying, but it's rarely a sign of a broken Mac. Nine times out of ten, clearing the quarantine attribute or re-downloading the file solves it. If you've tried everything and it still won't open, the app might genuinely be unsupported on your macOS version — check the system requirements before giving up.