macOS: "App" is damaged and can’t be opened. You should move it to the Bin
Gatekeeper is reporting a failed signature or notarisation check on a quarantined download, not a corrupted file. An app unzipped by a tool that dropped part of the bundle, modified after signing, or fetched from a mirror that never notarised it all end here, and the wording sends people to download it again instead of checking the signature.
Quick fix
Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.
# What Gatekeeper actually objects to
spctl -a -vvv /Applications/App.app
codesign -dv --verbose=4 /Applications/App.app
# The quarantine attribute is what triggers the check
xattr -l /Applications/App.app
# Notarisation, if the developer submitted and stapled it
xcrun stapler validate /Applications/App.app
# Your own build, broken by editing the bundle after signing: sign it again
codesign --force --deep --sign - /Applications/App.app
# Unzip with a tool that preserves bundle metadata
ditto -x -k App.zip /Applications/
# Removing the attribute skips the check, so keep it for software you built
xattr -d com.apple.quarantine /Applications/App.app
# For third party software, get it from the vendor and check the authority
codesign -dv --verbose=4 /Applications/App.app 2>&1 | grep AuthorityHow to diagnose Apple errors
macOS developer errors concentrate around three subsystems: the command line tools (xcrun and the active developer directory), the dynamic linker (dyld, library paths, and code signing), and Gatekeeper / notarisation. Apple Silicon added a fourth axis: architecture mismatches between arm64 and x86_64 binaries, which usually surface as confusing "library not loaded" or "bad CPU type" messages rather than as an explicit architecture error.
If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.
- Check the active developer directory first with
xcode-select -p. After every macOS or Xcode update this can point at a path that no longer exists, breaking git, compilers and package managers all at once. - For dyld errors, run
otool -L /path/to/binaryto list what it actually wants, then verify each path exists.DYLD_PRINT_LIBRARIES=1shows the resolution order at runtime. - Confirm architecture with
file /path/to/binaryanduname -m. On Apple Silicon, a Rosetta shell reportsx86_64and will silently install the wrong Homebrew prefix. - Homebrew lives at
/opt/homebrewon Apple Silicon and/usr/localon Intel. Permission errors under/usr/localon an M-series Mac almost always mean a Rosetta/native mix-up. - For Gatekeeper and notarisation, use
spctl -a -vvvto assess a bundle andxcrun notarytool logto get the actual rejection reason. The submission status alone tells you nothing useful.
Tools worth reaching for
xcode-select -potool -Lcodesign -dv --verbose=4spctl -a -vvvxcrun notarytool log
Authoritative references
Primary documentation for this error, worth reading before applying any fix in production.
Related Apple errors
- App Store Connect: ITMS-91053: Missing API declarationSince May 2024 Apple rejects uploads that call certain "required reason" APIs, such as…
- Homebrew: Cannot install under Rosetta 2 in ARM default prefixThe arm64 Homebrew in /opt/homebrew refuses to run in a translated process, which is what…
- Homebrew: Permission denied @ /usr/localHomebrew cannot write to its prefix because directory ownership is wrong, common on Intel…
- ld: symbol(s) not found for architecture arm64Compilation succeeded and the linker could not find a definition for something that was…
- macOS: cannot be opened because the developer cannot be verifiedGatekeeper blocked something that carries the quarantine attribute and is not notarised…
- macOS: dyld: Library not loadedThe dynamic linker could not find a shared library at the path baked into the binary, often…
- macOS: errSecAuthFailed / Keychain access deniedA code-signing or credential operation could not read the Keychain, common in CI when the…
- macOS: notarization failed (notarytool)Apple's notary service rejected the app, usually for unsigned/un-hardened binaries, a missing…
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Something missing or wrong?
This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.