How to Fix OSStatus Error 99999 on Mac

To install an app on your Mac, you can either download it from the Mac App Store or a trusted source and drag it to the Applications folder.

If you’re installing from the Mac App Store, you can directly install the app without doing anything else. But if you’re installing from a third-party source, you need to enable this function in System Preferences.

Installing an app on macOS is a lot less complicated compared to other operating systems. But it doesn’t mean that it is flawless all the time. One of the not-so-common errors encountered during app installation is the OSStatus error 99999. This error doesn’t occur much often, but when it does, you’d be left scratching your head for answers because this can be quite tricky to handle.

What Is OSStatus Error 99999 on Mac?

The OSStatus error 99999 usually happens after you install an app from a third-party source, regardless of whether it is an official or fake source. Even if you have enabled installing from a third-party source under System Preferences, there are still instances of this error message appearing and causing the app not to open.

This is probably due to Apple’s increasing campaign of keeping everything within the Apple system — Apple’s hardware needs to run only Apple software only. We all know that this is impossible so this error could be Apple’s way of forcing you to use the Mac App Store. But what if the app you want to install is not available there? Plus, there have also been reports of the OSStatus error 99999 appearing even when the app installed was from the Mac App Store.

Now, the problem does not lie with the installation process itself. The apps install just fine, but when you try to launch it, the app won’t open and you get this error message instead:

The operation couldn’t be completed.
(OSStatus error 999).

There is also no specific version affected by this error, which means that it can occur regardless of the macOS version your device is running on. Some users have encountered it in Sierra, High Sierra, Mojave, and even Catalina.

What Causes OSStatus Error 99999 on Mac?

If you’re downloading the app from a third-party source, you need to make sure that your Mac allows non-App Store applications to be installed in it. You need to enable this in System Preferences. If this is disabled, you will most likely encounter this error.

But if third-party installation is allowed on your Mac or the app you installed is from the Mac App Store, yet you encountered this error, then the cause is something else.

In some cases, the error appears due to a corrupted SystemPolicy file. Also known as the Gatekeeper, this security feature enforces the code signing and checks the downloaded applications before authorizing them to run. This verification process prevents you from accidentally or unknowingly executing malware. If Gatekeeper is corrupted, then it would have problems verifying your installation and come up with this error.

What To Do About OSStatus Error 99999 on Mac

If you’re getting this error when opening a newly-installed application, here’s some checklist you need to go through first before trying the fixes below:

• Restart your computer. Sometimes all your Mac needs is a fresh restart to resolve minor bugs and glitches.
• Clean up your device using a Mac cleaner to delete junk files that might be getting in the way of the running of your applications.
• Download the same application on another Mac to make sure that there is no problem with the installer and the app itself. If it runs properly on another device, then the fault is on your device.
• Make sure your Mac has enough storage space. If you have insufficient disk space, your apps won’t function properly.

If the problem doesn’t go away after doing all of the above, then it’s time to consider the solutions we’ve listed here:

Fix #1: Reinstall the App.

To make sure that the app was installed correctly and the installer was not corrupted, uninstall the app by dragging the icon from the Application folder to the Trash. Empty the Trash to ensure that everything is deleted. Next, download a new installer from your source and install it on your computer. If the app still fails to load due to OSStatus error 99999, proceed to the next step.

Fix #2: Enable Third-Party Installation.

If you’re downloading the app from the developer’s website or other trusted sources, make sure that macOS Gatekeeper is configured to allow such installations. To check the it is enabled, follow the steps below:

1. From the Apple menu, click System Preferences.
2. Choose Security and Privacy.
3. In the General tab, click the lock icon to make changes. You will need to type in your password and press Enter.
4. Once unlocked, the Allow apps downloaded from section will become clickable.
5. Tick off Anywhere to allow apps downloaded from any source to be installed and run on macOS.

If any of the other options are ticked off when you encounter the error, the steps above should quickly resolve it.

Fix #3: Restore the SystemPolicy Database.

If your Mac allows third-party installations and you’re still getting this error, then it might have something to do with your System Policy database.

To check whether it has been corrupted, you can do the SecAssessment system policy security command line utility by following the steps below:

1. Open Terminal from the Utilities folder.
2. Type in the following command, then press Enter:
   $spctl –assess –verbose –raw /bin/ls
3. If the result says: /bin/ls: unknown error 99999=1869f, this means that your SystemPolicy is corrupted.

To restore the default database, follow the instructions here:

1. In the Terminal window, type in the following command, followed by Enter:
   $ sudo cp /var/db/.SystemPolicy-default /var/db/SystemPolicy
2. Once the command has been executed, reboot your Mac.

After restarting, macOS should have restored its ability to install software. You can check this by reinstalling the app in question and launching it after installation. If it goes well, then your SystemPolicy database has been successfully restored.

Wrapping Up

The OSStatus error 99999 on Mac is an uncommon macOS problem that baffles a lot of Mac users, especially the non-techie ones. When trying to fix this error, make sure that you are comfortable with using Terminal because most of the fixes require entering commands. But once you understand the instructions carefully, you’ll understand that OSStatus error 99999 is not that difficult to resolve after all.