Fix "Blowhorn is damaged and can't be opened"
What to do when macOS says Blowhorn is damaged after you download it from blowhorn.ai or GitHub.
You download Blowhorn from blowhorn.ai or GitHub, install it, and open it. macOS shows a dialog saying Blowhorn is damaged and can't be opened, and tells you to move it to the Trash. Don't move it to the Trash yet.
A download from the site can save as Blowhorn-mac.dmg. That file is the
same release as the one on GitHub: a notarized, universal app signed with
an Apple Developer ID. macOS accepts a good copy of it, so this dialog
usually does not mean the release is bad. It usually means one of these:
- You opened the app while its copy from the disk image was still settling, and macOS checked it before the copy finished.
- You opened a different copy of Blowhorn than the one in Applications, for example from the Dock or Spotlight, or an older or locally built copy that isn't signed.
- The verdict is stale. On a Mac where an older Blowhorn was removed, or where more than one user account uses the shared copy in Applications, macOS can show this dialog for a copy that is actually fine. The dialog alone does not prove the release is bad.
Open the copy in Applications
-
Eject the Blowhorn disk image if it is still mounted. In the Finder sidebar, click the eject button next to Blowhorn.
-
In Finder, open the Applications folder and open Blowhorn from there. Don't open it from the Dock or Spotlight, which can point at another copy.
-
If the dialog comes back, clear the quarantine flag macOS put on the download. In Terminal, run:
terminal xattr -dr com.apple.quarantine /Applications/Blowhorn.appThen open Blowhorn from Applications again. This clears only the quarantine attribute on this Mac. The app stays signed and notarized.
-
If it still fails on this Mac, and on other computers that used the same download, contact support (see Get help) and say which version you downloaded. Support may ask you to compare the file's hash with the published one. Don't rebuild or repackage the app yourself.
If the copy checks out but the dialog keeps coming back
Verify the copy before you trust the dialog. In Terminal, run:
codesign --verify --deep --strict /Applications/Blowhorn.app
spctl -a -vv /Applications/Blowhorn.appA good copy ends with "valid on disk" and "satisfies its Designated Requirement", and spctl says "accepted" with source "Notarized Developer ID". If both pass, the dialog is wrong: click Cancel, never "Move to Trash", and clear the quarantine flag as above, then open Blowhorn from Applications again.
On a shared Mac, this matters twice over: the copy in Applications belongs to every account, so a dialog in one user's session must not delete it for the others. If the dialog appears in another user's session, that user should Cancel it rather than trash the shared copy.
If another copy of Blowhorn is opening
An older Blowhorn, or a local build that isn't signed, can be what the Dock or Spotlight opens. macOS checks that copy, not the one you just installed.
- Quit the other copy. Look for its menu-bar icon, or find Blowhorn in Activity Monitor and quit it there.
- Open Blowhorn from the Applications folder in Finder.
To see which version you have, select Blowhorn in Applications and choose File > Get Info.