How to Fix MacBook Overheating after Upgrade

Although problems with Macs overheating can happen anytime, many people will run into this issue after a major upgrade, like Big Sur. If you are experiencing this problem, you may also notice that your battery charge runs out quickly. Your computer may also be running slowly.

See also: How to Fix Big Sur Battery Drain Issues

If your Mac’s problem is related to a recent upgrade, there are steps you can take to diagnose and solve the issue. These are usually pretty effective, as the cause for the problem usually comes down to just a few common possibilities. There is also the possibility that an overheating problem is hardware related. In this article, we will give some troubleshooting steps to help you identify the cause of the overheating problem, and tell you how you can fix the issue.

Why your Mac is Overheating

After upgrading your macOS, there are processes that need to run in order to do things like index your files for searches (See: Mac Spotlight Search not Working after macOS Upgrade, Fix.) These processes can take a long time to complete and will be running in the background, long after your computer has “finished” upgrading. If you have recently, in the last day or so, upgraded, it might be best to wait and see if the problem resolves itself.


After upgrading to a new macOS, some of your apps may have become incompatible. Some of the apps that have been known to cause issues, at least until they were uninstalled/updated, are:

How to Fix It

To deal with apps that are causing problems after a new upgrade, the usual steps are:

  1. Identify which app is causing a problem.
  2. Uninstall/delete the app.
  3. Reinstall a new, updated (compatible) version of the app.

We will outline the basics here, but for more details on each of these steps, see our recent articles:

  1. Open a Finder window, then go to the menu bar at the top of your screen and select Go. Select Utilities from the dropdown menu.
  2. In the Finder window, double-click on Activity Monitor.
  3. Make sure the CPU tab is selected so you can view which processes are using the most CPU.
  4. See which process is using a large percentage of your CPU.
  5. Search (Google) for the name of that process to find out more information about where it comes from. This can help you identify the cause of your overheating problem. If you see that either accountsd or kernelmanagerd are the processes using too much CPU, see the links above. Those articles deal specifically with those two processes.
Activity Monitor


Various things can contribute to a MacBook overheating. If you have investigated the software angle and decided that everything looks ok there, you may want to look at physical (and more basic software) causes.

How to Fix It

Some of the simple things you can do are:

  1. Keep your macOS updated.
  2. Restart: Go to Apple menu  > Restart.
  3. Use your Mac on a flat surface.
  4. Clean airflow vents on your Mac.
  5. Quit apps you are not using.
Software Update

Reset SMC

The SMC controls power, lights and sensor functions on your MacBook. Resetting can fix a variety of issues.

  1. To reset the SMC, Shutdown/power off your MacBook.
  2. Press and hold 3 keys: Shift, Control and Option.
  3. Press and hold the power button, without releasing the other 3 keys.
  4. Hold all keys for 10 seconds, then release.
  5. Press the power button on your Mac.

Apple Diagnostics

Using this tool can help diagnose hardware problems.

  1. Disconnected all external peripherals from your MacBook except your mouse and power connection.
  2. Place your Mac on a hard surface.
  3. Turn off your Mac by going to the Apple menu > Shut Down.
  4. Turn on your Mac and immediately press and hold the D key. Keep holding the D key until you see the language screen.
  5. Select your language.
  6. Your Mac will perform the diagnostics. It will take a few minutes to complete. If your Mac finds any problems, the reports and possible solutions will be reported. The report will reveal if the fan and temperature sensors are working correctly.

For more details, see our article on How To Keep Your MacBook From Overheating.

Other Options


If you feel that the new upgrade just isn’t going to work out for you, you can downgrade to a previous macOS. For more details, see our article: How to Downgrade from MacOS Big Sur to Catalina.


Reinstalling will erase your disk! You must make a backup before reinstalling macOS.

  1. Back up your Mac using Time Machine.
  2. Restart your Mac in Recovery Mode:
    1. Power on your Mac. Immediately hold down 2 keys: Command (⌘) and R.
    2. Release when the Apple logo appears.
  3. Choose Reinstall macOS Big Sur. Then click Continue. Follow onscreen instructions. Note: if you choose to Reinstall from Time Machine Backup, you may end up with the exact same problem. That is why you are installing a fresh version of macOS.
  4. Recover your data from Time Machine. For any third-party apps, we suggest downloading the latest version from the developer’s website, in case one of these apps was causing your overheating problems.
    1. Connect your backup disk.
    2. Open a Finder window. From the menu bar at the top of your screen, select Go, then Utilities.
    3. Double-click on Migration Assistant in the Finder window.
    4. Choose to transfer from a Time Machine backup. Click Continue.
    5. Select the Time Machine backup you want to use. Click Continue.
    6. Select the information you want to transfer. Click Continue. If you are transferring a large amount of data, this could take hours to complete.

Apple Support

If the tips above haven’t helped resolve your issue and you need further assistance, you can contact Apple Support.

Recent Articles:

Dr. Stacey Butler is a tech writer at macReports covering news, how-tos, and user guides. She is a longtime Mac and iPhone user and holds a Ph.D. from the University of Illinois at Champaign-Urbana. Here is her LinkedIn profile.

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