Quick Summary
The "System Extension Blocked" error on macOS indicates that a software program's attempt to install a system extension (a piece of code that extends the operating system's functionality) has been prevented by macOS's security features. This usually happens because the system extension hasn't been properly authorized by the user.
Common Causes
- Unapproved System Extension: The most common cause is that you installed software that requires a system extension, but you didn't explicitly allow the extension in System Preferences. macOS requires user authorization for system extensions to run to protect against malicious software.
- Security Preferences: macOS's security settings are configured to block unsigned or improperly signed system extensions. This is a security measure to prevent potentially harmful software from being installed.
- Outdated macOS Version: In some cases, older versions of macOS may have stricter security policies or compatibility issues that lead to blocking valid system extensions. Some developers might target a newer version of macOS for security reasons.
- Conflicting Software: Another software installation on your system might conflict with the extension you are trying to permit. The two pieces of software might request the same operating system resources which is triggering the block.
Step-by-Step Fixes
Method 1: Allow the System Extension in System Preferences
Step 1: After the "System Extension Blocked" alert appears, immediately go to System Preferences.
Step 2: Click on Security & Privacy. The alert should be visible near the bottom of the pane, next to the text 'System software from developer "[Developer Name]" was blocked from loading.'
Step 3: Click the Allow button. You may need to click the lock icon in the bottom left corner and enter your administrator password to make changes.
Step 4: If the Allow button is not present, try restarting your Mac and repeating steps 1-3 immediately after logging in. The prompt to allow the extension is only available for a limited time after the software attempts to load the extension.
Method 2: Reinstall the Software
Step 1: Uninstall the software that requires the system extension.
Step 2: Restart your Mac.
Step 3: Reinstall the software. Pay close attention during the installation process for any prompts related to system extensions. Make sure you allow the extension immediately after installation, following the steps in 'Allow the System Extension in System Preferences'.
Method 3: Disable System Integrity Protection (SIP) - Advanced Users Only
Warning: Disabling SIP weakens your system's security. Only proceed if you understand the risks.
Step 1: Restart your Mac in Recovery Mode. To do this, restart your Mac and hold down Command (⌘) + R until the Apple logo appears.
Step 2: In the macOS Utilities window, select Utilities > Terminal.
Step 3: Type csrutil disable in the Terminal and press Enter.
Step 4: Type 'reboot' and press Enter.
Step 5: After your Mac restarts, try installing or running the software again. If it works, you can either leave SIP disabled (not recommended) or re-enable it.
Step 6: To re-enable SIP, repeat steps 1-2, but type csrutil enable in the Terminal instead of disable. Then, reboot your machine.
Method 4: Check for Software Updates
Step 1: Open the App Store application.
Step 2: Click on Updates in the sidebar.
Step 3: Install any available updates for macOS and the software you're trying to use.
Step 4: Restart your computer after the updates have installed.