How to Solve the Mac Error Code 100006: Simple and Quick Solutions

The macOS error code 100006 is a common issue that prevents apps from opening on your Mac. This error is followed by a “The operation can’t be completed because an unexpected error occurred” message. It indicates that there is a problem with the app’s code signature, which is used to verify the app’s integrity. Although frustrating, the 100006 error can typically be fixed with a few simple steps.

error code 100006

In this article, we will walk through what causes this error, as well as several solutions to resolve error 100006 and get your apps opening again.

Let’s get started.

Also read: Best Ways To Fix Mac Error 102

What is the Error Code 100006 on Mac?

The 100006 error code on Mac indicates that an app cannot be opened due to a code signature issue. Specifically, it means that the code signature for the app is missing or invalid. The code signature contains encrypted information that allows the operating system to verify that the app is from the original developer and has not been tampered with.

If this signature is damaged or corrupted in any way, you will see the 100006 error when trying to launch the app. This is a security measure implemented in macOS to ensure the integrity and security of apps.

How to Fix Error Code 100006 on macOS?

Step 1: Restart Your Mac

The first step you should take when encountering the 100006 error is to restart your Mac. A simple restart can often clear out any temporary glitches, memory issues, or small errors that may be causing the code signature error. Shut down your Mac completely, wait at least 10 seconds, then turn it back on and try to open the app again.

Restart Your Mac

Restarting refreshes the computer’s memory and reloads any crucial system components that may have been experiencing issues. Many users find that this quick restart solves the 100006 error immediately.

Step 2: Update Your Apps

If restarting did not work, the next thing to try is updating your apps. Outdated app versions can sometimes trigger the 100006 error due to compatibility issues with the current macOS version.

Update Your Apps

Open the App Store on your Mac and click on the Updates tab. Install any and all available updates. This will update the app code itself as well as any frameworks or dependencies used by the app. Updating brings your apps to the latest stable versions which have fixes for a variety of bugs, including any related to the code signature.

After updating apps, try launching the problematic app again. In most cases, the simple act of updating to the latest version resolves the error code 100006 Mac signature error. Updates through the App Store are the best way to easily get the most current app versions.

Also read: How to Fix Verifying Microsoft Outlook Mac Stuck Error (6 Solutions)

Step 3: Reset NVRAM

Resetting the NVRAM (non-volatile RAM) can clear out any corrupted files that may be contributing to the 100006 issue. NVRAM stores system settings and file locations that are used when your Mac boots up. A damaged NVRAM file can cause errors in locating the proper app code signature. Here is what you need to do:

Step a: To reset the NVRAM, first shut down your Mac entirely.

Step b: Now, turn it back on and immediately press and hold Command + Option + P + R.


Step c: Keep these keys pressed down until you hear your Mac restart and the startup chime a second time.

This will wipe and restore the NVRAM to the factory default settings. Now try opening the app again normally.

Step 4: Delete and Reinstall the App

If you still see the error code 100006, the next step is to delete and reinstall the problematic app:

Step a: First, drag the app to the Trash to fully delete it from your system. Then empty the Trash.

Delete and Reinstall the App

Step b: Re-download a fresh copy of the app from the App Store or developer’s website. Make sure to download the latest version.

Step c: Follow the installation instructions to reinstall the app on your Mac.

Deleting the app and reinstalling removes any corrupted framework files that may be linked to the app itself. A fresh install often resolves the code signature error by overwriting damaged files with a new, clean copy. Be sure to download from a trusted source like the App Store for guaranteed integrity.

Also read: How To Fix Error Code -8084 On Mac

Step 5: Check Security and Antivirus Software

Antivirus, firewalls, and other security software can sometimes interfere with applications and cause code signature errors like 100006. The security software may mistakenly identify part of the app’s code as a threat and attempt to block it from running. To test if this is the case:

Step a: Open System Preferences > Security & Privacy on your Mac.

Step b: Temporarily disable any antivirus or firewall software.

Check Security and Antivirus Software

Step c: Try launching the app again after disabling your security software.

If the app now opens, you will know your security software is conflicting with the code signature. You may need to add exceptions for the problematic app. Re-enable your security software after testing. Be sure to disable security programs temporarily as a test.

Step 6: Reset File Permissions on Your Hard Drive

Permission issues with system files can also lead to error code 100006 preventing apps from launching properly. Resetting your hard drive permissions can clear up any problems with apps accessing the system files they need to run.

To reset permissions:

Step a: Reboot your Mac into Recovery Mode by restarting and holding Command + R.

Step b: When in Recovery Mode, select Disk Utility and click Continue.

Step c: Select your hard drive and click the First Aid tab.

Reset File Permissions on Your Hard Drive

Step d: Click the “Repair Disk Permissions” button.

This will check and reset any incorrect permission settings on system files, allowing apps to access what they need to function normally again. Try opening the app once permissions have been reset.

Also read: How To Fix “Couldn’t Unmount Disk” Error On Mac

Step 7: Contact the Developer

If you still cannot resolve error 100006, reach out to the developer of the app directly for further troubleshooting assistance. They may need to issue a patched version of the app to fix the specific code signature error you are encountering. When contacting the developer, provide details like:

  • The full error message (e.g. “App can’t be opened because of a problem. Check with the developer for possible fixes.”).
  • Steps you’ve taken trying to resolve the issue.
  • Your Mac model and macOS version.
  • Whether the app had opened correctly before.

With this information, the developer can look into the issue on their end and provide steps or an updated app to fix the 100006 error. Most developers will be happy to help troubleshoot and get their app working again.


The 100006 error in macOS can prevent important apps from launching but fixing it is usually straightforward. A simple restart, update, reinstallation or NVRAM reset will resolve many cases. For continuing issues, check security software conflicts, reset hard drive permissions, or contact the developer.

With persistent troubleshooting, you can clear error 100006, restore your code signatures, and regain access to vital Mac applications.

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