Reinstalling macOS essentially involves erasing your Mac’s disk drive and installing a fresh copy of the operating system. This is done using the Recovery options in macOS. Some reasons why someone may want to reinstall macOS include:
- Their system is running slowly or acting glitchy
- They want to start fresh and remove any unused apps or files
- An update to macOS caused problems
- They are selling their Mac and want to wipe it
Reinstalling the OS can help resolve issues caused by system file corruption or clutter. It also resets the computer to factory settings. However, there are also downsides to reinstalling macOS that need to be considered.
Back Up Your Data
It is critically important to back up your data before reinstalling macOS. A clean install will completely wipe your Mac’s hard drive, erasing all files, applications, and system settings (Restore your Mac from a backup). Therefore, you’ll want to ensure your important documents, photos, music, and other personal data are safely backed up before proceeding.
The recommended way to back up a Mac is using Apple’s Time Machine software. Time Machine makes automatic incremental backups of your files to an external hard drive or network location. Before reinstalling macOS, make sure you have a recent Time Machine backup that you can restore from later (Back up and restore your Mac).
If you don’t use Time Machine, you should manually back up your files by copying them to an external hard drive or cloud storage service. Make sure not to skip anything important. After reinstalling macOS, you can then copy your files back from the backup.
Backing up beforehand avoids the risk of permanent data loss during the macOS reinstallation process. Be sure to verify your backup was successful before erasing your Mac.
Understand the Pros
There are several potential benefits to erasing your Mac’s disk and reinstalling macOS. Some of the main advantages include:
- Clearing out clutter and freeing up disk space – Over time, residual files, caches, and other unused data can accumulate and take up precious storage space. Reinstalling macOS essentially gives you a “clean slate” by wiping the disk and starting fresh.
- Fixing software issues or instability – If you’ve noticed odd app crashes, freezes, or other glitches, these problems are sometimes fixed by a fresh macOS install. It can clear out any corrupted files or settings.
- Improved performance – With all the clutter removed and a fresh OS, apps and system functions may run faster and smoother after reinstalling macOS.
- Easier troubleshooting – If you’re having an unresolved problem, wiping the disk helps rule out any software-related causes.
- Remove malware or viruses – Though rare on Macs, a full reinstall can wipe out any malicious software that standard antivirus tools may have missed.
Overall, reinstalling macOS offers a chance to reset your Mac if you feel it’s become too cluttered or slow over time. As Apple notes, it’s a good way to “start over and clean up your Mac.” Just be sure to properly back up your data first.
Understand the Cons
There are several downsides to consider before deciding to reinstall macOS:
It can be very time consuming. The reinstallation process itself can take over an hour, especially if you are redownloading the OS over the internet. After that, you’ll need to reconfigure all of your settings, redo your desktop customizations, reinstall all your apps, and get your files organized again. This can easily take several hours or longer.1
You may lose data if you don’t properly back up. If you don’t securely back up all your files and data before reinstalling, you risk permanently losing photos, documents, settings, app data, and other important information.
It can cause programs and apps to not work properly. Some apps rely on certain system files or configurations to work correctly. Reinstalling macOS puts everything back to factory settings, which can cause crashes or bugs in apps you had customized and optimized.
It will require reinstalling all your apps. After reinstalling the OS, you’ll have to go through the tedious process of re-downloading and reinstalling all your applications. This alone can take hours depending on how many apps you use.
It may not fix any problems. There’s no guarantee that wiping your Mac will resolve whatever issues you were having. The problems could still persist even after spending time reinstalling the OS.
You’ll need to re-customize your settings. All of your system preferences, account settings, desktop wallpaper, dock configuration, and other customizations will be lost. You’ll have to manually set them up again.
When You Should Reinstall
There are a few situations where experts recommend reinstalling macOS to resolve issues or prepare your Mac for sale:
If you are experiencing major software problems that you can’t resolve through regular troubleshooting, a fresh install of macOS may help. Issues like persistent crashing, freezing, performance problems, or corruption could potentially be fixed by erasing the drive and starting fresh (Source: https://www.makeuseof.com/tag/mac-users-good-reason-ever-reinstall-os-x/). Make sure to exhaust other troubleshooting options first and back up your data.
Before selling or gifting your Mac to someone else, it’s highly recommended to wipe the drive and reinstall macOS. This will erase all of your personal data and custom settings, allowing the new owner to start with a clean slate (Source: https://support.apple.com/guide/mac-help/reinstall-macos-mchlp1599/mac).
If you are upgrading to a new major version of macOS and want to start completely fresh, a clean install can allow you to fully transition to the new OS. This avoids upgrading on top of old files or settings that may cause conflicts.
Reinstalling can also be useful if you want to partition or reformat your drive and change the file system. It’s best to start with a blank disk when making major disk changes.
When You Shouldn’t Reinstall
In many cases, reinstalling macOS is unnecessary and won’t solve your issues. According to discussions on Reddit, there’s no need to reinstall macOS just to “clean things up” when you notice minor performance issues or things “acting weird” (source: https://www.reddit.com/r/MacOS/comments/16sxz00/do_any_of_you_reinstall_macos_to_clean_up_every/). Small software problems can often be fixed by troubleshooting the specific app or service, updating software, clearing caches, or restarting your Mac.
Reinstalling the operating system is also not required just to free up storage space. There are many other ways to clear storage on your Mac without reinstalling macOS, like deleting unused apps and files, emptying the trash bin, offloading photos to the cloud, or using built-in storage optimization tools. Unless you’re experiencing severe performance issues or crashes directly caused by a lack of free space, reinstalling macOS is an overly drastic measure.
In general, if your Mac is functioning properly but you’re experiencing isolated issues with an app or service, reinstalling the entire operating system is likely unnecessary. Focus on troubleshooting the specific problem first before resorting to completely reinstalling macOS.
How to Reinstall macOS
Here is a step-by-step guide to erasing your Mac’s disk and reinstalling macOS from scratch:
- Backup your data. Make sure to backup any important files, photos, or documents you want to keep before erasing your disk. You can use Time Machine or manually copy files to an external hard drive.
- Restart your Mac into Recovery Mode. To do this, restart your Mac and hold down the Command + R keys immediately after you hear the startup chime. This will boot your Mac into Recovery Mode.
- Erase your disk. In the Recovery Mode menu, select Disk Utility. Then click “Erase” to erase your disk. This will delete all data and apps, preparing it for a clean install.
- Reinstall macOS. After erasing, quit Disk Utility. Select “Reinstall macOS” from the Recovery Mode menu and follow the prompts to reinstall the operating system.
- Set up your Mac. The reinstallation will require you to go through the initial setup prompts like when you first got your Mac.
- Reinstall apps and restore data. Once setup, you can redownload apps from the App Store and restore your files from your backup.
Following these steps will completely erase your Mac’s disk and allow you to freshly install the latest macOS from scratch.
Reinstalling Apps and Settings
After reinstalling macOS, one of the biggest challenges is getting your apps and settings back to how they were before. Here are some tips for smoothly reinstalling apps, settings, and data:
Apps purchased through the Mac App Store can easily be redownloaded by going to the Purchased tab and selecting the apps you want to install again. For apps not purchased through the App Store, check if the developer offers a direct download of the app from their website. You may need to re-enter your license key.
The Migration Assistant tool (located in Applications > Utilities) can help transfer settings, files, and user accounts from a Time Machine backup or external drive. Be sure to have a current backup before reinstalling macOS.
Signing into iCloud after reinstalling can restore contacts, calendars, notes, bookmarks and more. Double check that everything synced properly. You may need to manually transfer some files from a backup.
For browser settings and passwords, signing into your Google, Firefox, or Safari account can help restore preferences. Bookmark files may need to be imported manually.
Reinstalling apps like Microsoft Office or Adobe Creative Cloud will require signing in with an account to download the apps again. Be prepared with your login information.
Take time before reinstalling to note down important settings or customizations. This will help you get back to your preferred setup smoothly.
Alternatives to Reinstalling
Before choosing to erase and reinstall macOS, it’s worth considering some alternatives that may resolve issues without requiring a full system reinstallation. Some other options include:
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Using macOS recovery to reinstall the OS while preserving user data and settings. This refreshes the system files without erasing everything.
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Running Apple’s maintenance scripts to fix common issues like corrupted caches or permissions problems.
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Reinstalling specific problem apps instead of the whole OS. Apps can often be reinstalled without losing data or settings.
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Using Disk Utility’s “Repair Disk” option to fix disk errors like file corruption or directory damage.
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Trying third-party system maintenance tools to clean caches, uninstall apps, or identify issues before reinstalling.
While a full erase and reinstall is sometimes necessary, exploring these alternatives first may resolve problems without the hassle of a complete OS reinstallation.
Conclusion
In summary, reinstalling macOS can be a useful troubleshooting step for resolving software issues, improving performance, or wiping your Mac before selling. However, it is not necessary for routine maintenance and can be time consuming to reinstall apps and settings. Consider reinstalling macOS if you are experiencing persistent crashes, slowdowns, or software conflicts. But avoid reinstalling just for minor issues that can likely be resolved through less drastic measures. Before reinstalling, be sure to backup your data. Reinstall macOS from the Recovery partition or a bootable installer drive. Overall the decision depends on your specific situation – but in many cases cleanup tools, updates, or targeted troubleshooting may be preferable to a full macOS reinstallation.
As a final recommendation, only reinstall macOS if you are technically comfortable doing so and have exhausted other troubleshooting options. Reinstall as a last resort for major software problems versus doing it preemptively. And always backup your data first. When in doubt, consult with Apple support or a technician before taking the step of erasing your drive. Handle the reinstallation process carefully by following Apple’s instructions.