How to fix You do not have permission to open the application. Contact your computer or network administrator for assistance

The error “You do not have permission to open the application. Contact your computer or network administrator for assistance” on macOS typically stems from Gatekeeper blocking an unsigned or unnotarized app.

Her I am using Homebrew to install UPX and then running sudo upx -d followed by the application name—trying to unpack or modify the app to bypass this issue.

Here are the suggested fix to that problem: –

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Step 1: Install Homebrew and UPX

Install Homebrew (If Not Already Installed)

• Open Terminal:
  • Go to Applications > Utilities > Terminal.
• Install Homebrew:
  • Run:
    /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
  • Follow prompts: Agree to Xcode Command Line Tools installation (if prompted) and enter your admin password.
  • Add Homebrew to your PATH (if not automatic):
  • Intel Macs:
    echo 'eval "$(/usr/local/bin/brew shellenv)"' >> ~/.zshrc
  • Apple Silicon:
    echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zshrc
  • Reload shell:
    source ~/.zshrc
• Verify:
  • brew --version should output a version (e.g., “Homebrew 4.x.x”).

Install UPX

• Install UPX via Homebrew:
  • Run:
    brew install upx
• Verify:
  • Check the version:
    upx --version
  • Output should be something like “upx 4.x.x”.

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Step 2: Attempt sudo upx -d on the Application

Your suggestion is to use sudo upx -d followed by the app name. Let’s try this, though it’s unlikely to resolve the Gatekeeper issue directly unless the app is a compressed executable.

• Locate the App:
  • Find the app in Finder (e.g., /Applications/MyApp.app or ~/Downloads/MyApp.app).
• Run UPX Decompression:
  • In Terminal, use:
    sudo upx -d /path/to/MyApp.app
  • Example:
    sudo upx -d /Applications/MyApp.app
  • Enter your admin password.
• Expected Outcome:
  • If the app is UPX-compressed, this decompresses it. Output might look like:
    Ultimate Packer for eXecutables UPX 4.x.x File size Ratio Format Name 123456 -> 789012 63.87% macos/app MyApp.app Unpacked 1 file.
  • If it’s not compressed or not a valid UPX target, you’ll see:
    UPX: /path/to/MyApp.app: NotPackedException
• Test the App:
  • Double-click the app. If the error persists, UPX isn’t the solution—proceed to Step 3.

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Step 3: Fix the Gatekeeper Permission Error (Effective Solution)

Since upx -d likely won’t address Gatekeeper’s permission block (it’s a security policy, not a compression issue), here’s how to fix it properly:

Option 1: Allow via System Settings

• Try Opening the App:
  • Double-click the app in Finder. You’ll see the error.
• Open System Settings:
  • Apple menu () > System Settings > Privacy & Security (or Security & Privacy on macOS 12 or earlier) > General.
• Approve the App:
  • Look for “‘MyApp.app’ was blocked” and click Open Anyway.
• Retry:
  • Double-click the app—it should open after entering your admin password (if prompted).

Option 2: Remove Quarantine via Terminal

• Open Terminal:
  • Run:
    sudo xattr -r -d com.apple.quarantine /path/to/MyApp.app
  • Example:
    sudo xattr -r -d com.apple.quarantine /Applications/MyApp.app
  • Enter your admin password.
• Launch:
  • Double-click the app—it should work.

Option 3: Disable Gatekeeper Temporarily

• Disable Gatekeeper:
  • In Terminal:
    sudo spctl --master-disable
• Open the App:
  • Double-click it—it should launch.
• Re-enable Gatekeeper:
  • After use:
    sudo spctl --master-enable

Option 4: Right-Click Open

• Bypass:
  • Right-click the app in Finder > Open > Click Open in the dialog.
• Why: Adds an exception without changing system settings.

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Why sudo upx -d May Not Work

• Purpose: UPX decompresses packed executables (e.g., .exe, .app binaries), but macOS apps are bundles (folders with .app extensions) containing multiple files. Gatekeeper blocks based on signatures and quarantine flags, not compression.
• Gatekeeper: The error is a security restriction, not a file format issue. Modifying the app with UPX might even break it if it’s not designed for compression.

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Troubleshooting

• UPX Error:
• If upx -d fails (e.g., “NotPackedException”), the app isn’t UPX-compressed—skip to Step 3.
• Permission Still Denied:
• Verify the app path (drag it into Terminal) and ensure sudo is used correctly.
• App Damaged:
• Check:
  codesign -vv /path/to/MyApp.app
• If “invalid” or “revoked,” redownload from a trusted source.
• macOS Version: Works on Big Sur and later (April 6, 2025). Older versions may need slight tweaks.

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What app are you trying to open ?