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Why Mac Diagnostics Doesn’t Run? 7 Reasons & Their Fixes

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Last updated: September 6, 2023

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You’re working on your Mac and notice it’s running slower than usual. You decide to run Mac Diagnostics to see if there’s an issue with your hardware or memory, but to your surprise, it won’t start. You’re left wondering why Mac Diagnostics doesn’t run and what you can do to fix it. 

Mac Diagnostics is essential for any Mac user, and encountering an error when running it can be frustrating. In this blog post, I’ll explore the reasons behind the error and provide solutions for running Mac Apple Diagnostics.

Before We Begin

Mac Diagnostics is a useful tool that helps resolve various Mac-related issues, and if it stops working, the diagnosis becomes difficult. However, you can use MacKeeper to track updates and malware issues obstructing Mac Diagnostics. So, download it now and eliminate all your Mac Diagnostics problems.

Common Reasons Why Mac Diagnostics Doesn’t Run

Mac Diagnostics is a built-in utility tool that allows users to diagnose hardware and software issues on their Mac. However, there are times when Mac Diagnostics may not run, which can be frustrating for users who need to diagnose and troubleshoot their Mac.

Here are some common reasons why Mac Diagnostics doesn’t run:

  • 🔍 Outdated Operating System: Mac Diagnostics requires a certain operating system version to run. If your Mac is running an outdated operating system, it may not be compatible with the version of Mac Diagnostics you are trying to run.
  • 💻 Hardware Issues: Mac Diagnostics is designed to diagnose hardware issues on your Mac. If your Mac is experiencing hardware problems that prevent it from starting up or running, Mac Diagnostics may not be able to run either.
  • 🔧 Software Conflicts: Sometimes, other software running on your Mac can conflict with Mac Diagnostics, preventing it from running properly. It can be caused by antivirus software, firewall software, or other system utilities.
  • 🙅 User Error: In some cases, Mac Diagnostics may not run because of user error. It can happen if you don’t follow the correct steps to start up Mac Diagnostics or if you don’t have the necessary permissions to run the tool.
  • 🦠 Malware or Virus Infections: Malware or virus infections can also prevent Mac Diagnostics from running. It is because malware or viruses can interfere with the normal functioning of your Mac, including the operation of diagnostic tools like Mac Diagnostics.

How to Fix Mac Diagnostics Doesn’t Run

When Mac Diagnostics fails to run, diagnosing and resolving any potential hardware problems can be challenging. The following techniques can help you resolve this problem and get your Mac running smoothly again.

1. Restart Your Mac

Restarting your Mac can fix various issues, including the Mac Diagnostics not working. Restarting your Mac clears the memory, restarts the system software, and resolves problems causing the Mac Diagnostics malfunction.

To restart a Mac, follow these steps:

  1. Click the Apple logo in the top-left corner of the screen.
  2. Select Restart from the dropdown menu.
click the apple icon and select restart
  1. A confirmation window will appear. Click Restart again.
click restart to confirm your decision
  1. Wait for your Mac to shut down and restart. It may take a few minutes.

2. Reset the SMC

Resetting the System Management Controller (SMC) on a Mac can help resolve various hardware and power-related issues. While it may not specifically target the Mac Diagnostics not running issue, performing an SMC reset can potentially address underlying problems preventing the diagnostics tool from functioning properly.

To reset the SMC on your Mac, follow these steps:

  1. Click the Apple menu in the top-left corner and select Shut Down.
click the apple icon and select shut down
  1. Unplug your Mac from the power source if it is connected to a power adapter.
  2. Hold the Shift + Control + Option  keys and the Power button simultaneously on your Mac’s built-in keyboard for about 10 seconds.
macbook air ctrl shift option key
  1. After 10 seconds, release all the keys and the Power button.
  2. If your Mac was connected to a power adapter, reconnect it to the power source.
  3. Press the Power button to turn on your Mac.
macbook air touch id


Performing an NVRAM/PRAM reset is helpful when incorrect settings cause the Mac Diagnostics not working. Resetting these memory modules will clear any stored settings that might be causing the issue and can help resolve the problem. You don’t need to back up as it will not erase any data from your Mac.

To reset the NVRAM/PRAM, follow these steps: 

  1. Shut down your Mac. 
  2. Press the Power button to turn on your Mac. 
macbook air touch id
  1. Immediately press and hold the Command + Option  + P + R keys.
macbook air option command p r keys
  1. Hold down the keys until you hear the startup sound twice or see the Apple logo twice. Release the keys and let your Mac continue to start up.

4. Update Software

Software updates often include bug fixes and patches that address known issues and improve system stability. By updating macOS, you address any known bugs or glitches affecting Mac Diagnostics. It also ensures all the necessary components are up-to-date and compatible with the diagnostics tool.

Here are the steps to update your macOS on Mac:

  1. Click the Apple logo in the top-left corner and select System Settings.
click the apple icon and select system settings
  1. Click General and select Software Update.
click general and select software update
  1. If any updates are available, click Update Now and follow the instructions.
click update now in software update
  1. If the updates require restarting your Mac, save your work and click Restart.
click the apple icon and select restart 1

After the restart, check if it is working correctly. If it’s not, move on to the next solution

5. Boot in Safe Mode

Safe Mode is a troubleshooting mode designed to start up your Mac with the minimum required software, allowing you to isolate and diagnose problems with your system. When you boot your Mac in Safe Mode, it performs a series of checks and disables all third-party software, startup/login items, and non-essential hardware components.

Here’s how you can boot your Mac in Safe Mode to resolve Mac Diagnostics doesn’t run:

  1. Shut down your Mac.
  2. Press the Power button to turn on your Mac.
macbook air touch id
  1. Immediately press and hold the Shift key as your Mac starts up.
macbook air shift key
  1. Release the Shift key when you see the login window.

6. Reinstall macOS

Reinstalling the OS is a more advanced solution. It can help fix software-related issues causing Mac Diagnostics doesn’t run error. However, it’s time-consuming and should only be used as a last resort if the previous methods have failed to resolve the issue.

Before proceeding with this solution, back up all the important data on your Mac to avoid losing any information.

To reinstall macOS on a Mac, follow these steps:

  1. Start by backing up all important data on your Mac to an external hard drive or cloud storage service.
  2. Restart your Mac and hold down the Command + R keys until the Apple logo appears.
macbook air command r keys
  1. The Mac will start in recovery mode, and you will see a window with several options.
  2. Select Reinstall macOS and click Continue.
macos recovery screen
  1. Follow the instructions to complete the reinstallation process. This may take some time, depending on your Mac’s speed and the OS’s size.
  2. Once the reinstallation process is complete, your Mac will restart, and you can check if the keyboard backlight issue has been resolved.

7. Scan for Malware Using MacKeeper

Malware can corrupt your Mac Diagnostics. If you suspect malware is the cause of problems with Mac Diagnostics, use an antivirus application to remove it. I personally use MacKeeper and recommend it to everyone.

Here’s how you can run a malware scan on your Mac using MacKeeper:

  1. Download and install MacKeeper.
  2. Open MacKeeper on your Mac and click the Antivirus tab in the left-hand menu.
click antivirus under the security section
  1. Click the Start Scan button to scan your system for malware and viruses.
click start scan in mackeeper antivirus
  1. Wait for the scan to complete, which may take several minutes, depending on the size of your system and the number of files being scanned.
  2. Once the scan is complete, MacKeeper will display a list of issues. Review the list of issues and click the Fix button to resolve them.
  3. Once the fixes are complete, you may be prompted to restart your system to complete the repairs.
  4. If no threats are found, click the Rescan button to run the scan again or close the program.
click restart to finish the process

What Else Can MacKeeper Do?

Besides scanning for malware, MacKeeper can free up RAM, remove duplicate files, and manage login items on your Mac. Check out my detailed MacKeeper review to learn more about its amazing features to optimize your Mac. 

Final Words

If Mac Diagnostics doesn’t run, it can be frustrating, but there are several steps you can take to resolve the problem. I have outlined all possible solutions to this issue in this guide. Here are some more Mac optimization tips for the future:

Frequently Asked Questions

  1. How can I fix the issue of Mac Diagnostics not running?

    You can fix the issue of Mac Diagnostics not running by restarting the Mac and trying again, booting your Mac in Safe Mode, resetting the System Management Controller (SMC), and reinstalling macOS.

  2. Can I run diagnostic tests on my Mac without using Mac Diagnostics?

    Yes, you can run diagnostics tests on your Mac without using Mac Diagnostics. There are third-party diagnostic tools available that you can use to test the hardware components of a Mac, such as TechTool Pro, DriveDx, and MemTest.

  3. How often should I run diagnostic tests on my Mac?

    You should run diagnostic tests on your Mac periodically, such as once every few months or after any major hardware or software changes. It can help identify and prevent potential issues before they become serious problems.

Hashir Ibrahim


I'm Hashir, a tech journalist with a decade of experience. My work has been featured in some of the top tech publications like MakeUseOf and MakeTechEasier. I have a bachelor's degree in IT, a master's in cybersecurity, and extensive knowledge of Apple hardware, specifically MacBooks. As the senior writer at MacBook Journal, I write in depth guides that help you solve any issues you have with your mac and unbiased reviews that help you make the right buying decisions.



Hi there! I'm Ojash, a tech journalist with over a decade of experience in the industry. I've had the privilege of contributing to some of the world's largest tech publications, making my mark as a respected Mac expert. My passion lies in exploring, using, and writing about MacBooks, and I enjoy sharing my expertise to help others make informed decisions and get the most out of their MacBook experience. Join me as we delve into the fascinating world of MacBooks together!

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