In the Disk Utility sidebar, select the Mac’s startup drive (not the volume or the container, but the top-most item in the startup drive hierarchy). Click or tap the Erase button. In the sheet that drops down, give the drive a name, set the format to Mac OS Extended (Journaled), and the Scheme to GUID Partition Map. Restart your Mac again and use Command +R to open OS X utilities. Select Reinstall OS X. Click continue on OS X El Capitan Installer. Proceed with the installation. You have completed the roll back process. Now, you just need to restore your El Capitan data using the Time Machine backup you have. Restoring data from Time Machine Backup. Select Time Machine Backup from OS X utilities. If you’ve been a victim of such an issue, you might want to roll back the update on your Mac. Getting back to your favorite-old macOS version isn’t straightforward, though. There’s simply no option anywhere on your Mac that lets you downgrade macOS to an older version of the operating system.

Are you trying to revert or downgrade your new macOS or Mac OS X to the previous version on the Mac computer? If yes, stay here. Just follow the provided guidance below to bring your previous macOS or Mac OS X back without losing any data:

Workable Solutions	Step-by-step Troubleshooting
Method 1. Use Time Machine	Start Mac and hold Command + R keys > Enter Recovery Mode > Insert Time Machine drive...Full steps
Method 2. Use USB Bootable Drive	Back up data first > Plug in USB and launch Disk Utility > Erase USB > Rename it as 'My Volume'...Full steps
Bonus Tip. Recover Data	After reverting macOS or Mac OS X, run EaseUS Mac file recovery software > Scan and recover lost data ...Full steps

Methods on this page can be applied to all Mac systems including the latest Big Sur, Catalina, Mojave, High Sierra, Sierra, and old Mac OS El Capitan, etc.

Tip: Backup Mac data before downgrading macOS or Mac OS X

It's highly recommended for you to back up all important Mac data first before you start downgrading Mac OS to an older system.

You can either choose third-party Mac backup software to back up Mac data to an external hard drive at once or choose Time Machine to back up all wanted data with ease.

Considering data security, it's also highly recommended for you to backup all important data into an external hard drive.

If you prefer to use Time Machine, here are the details:

• Click 'Finder' > 'Preference'> Check 'Hard disks box' underShow these items on the desktop.
• Open the backup disk and create a file folder and name it, for example, 'My Backup'.
• Open the Mac disk and click'Users' file folder > Select all files and data that you want to back up and drag to the My Backup file folder.

Wait for the process to finish. After backing up all data, then you can start to revert macOS with ease. Here, you'll find two methods for you to downgrade macOS without losing data and you can choose either one as a guide.

Method 1. Downgrade macOS or Mac OS X with Time Machine

So if you have created backups for your Mac data and macOS, follow the below steps for a guide. If you haven't created such a backup, please jump to Method 2 to downgrade Mac OS.

1. 1. Start or restart your Mac and hold command+ R keys to enter theRecovery Mode, or hold the Option/Alt and then choose the Recovery option.
2. 2. Insert the hard drive used for Time Machine and chooseto Restore from Time Machine Backup under OS X Utility, choose the inserted hard drive.

1. 3. Choose the most recent data and time when the Mac was still running the current macOS.
2. 4. Select the main disk drive where the backup was stored and it is usually named Macintosh HD. Click Restore.

Then all you need is to wait for the computer to restore and gain Yosemite again. It will usually take a few hours or all day long, depending on how much data need to be restored.

Method 2. Create USB Boot Drive and Revert Back to Old macOS or Mac OS X

This method is set for users who have no Time Machine backups. And if you have no backups of your current macOS or Mac OS, use Time Machine to back up your important data first and the system first.

Then follow the below steps to downgrade Mac OS now: (The ways to download new macOS and old Mac OS X are different. Make sure that you've followed the right guide for downgrading the Mac system.)

Downgrade macOS (e.g: Downgrade macOS Mojave to High Sierra)

1. 1. Plug an external USB drive (with 16GB min), launch Disk Utility, and select the USB drive, click Erase.
2. 2. Rename the USB drive as 'MyVolume' and choose APFS or Mac OS Extended as the format, click Erase. Quit Disk Utility when the process is done.

3. To to Finder and launch Terminal, type: -sudo /Applications/Install macOS High Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install macOS High Sierra.app and hit Return.

1. 4. Enter your Admin Password as required, wait until the process is done.
2. 5. Restart the Mac, hold the Option key.
3. 6. When the option to select a boot disk appears, choose the installer disk (the external USB drive) you created.
4. 7. High Sierra will start the installing process. When it's finished, restart your Mac and the Startup Assistant will appear. Then go through the steps to set up your Mac.

If your Mac is shipped with Mojave, you can directly downgrade Catalina to Mojave with the below tips:

1. 1. Restart Mac, hold Command + Option + Shift + R keys to boot into Recovery Mode. You can also press Command + R to enter the Recovery Mode.
2. 2. Click on 'Disk Utility', select the disk with Mojave installed, and click 'Erase'.

1. 3. Rename the disk, select Mac OS Extended or APFS as the file format, click 'Erase'. Quick Disk Utility by then.
2. 4. Re-enter the Recovery Mode, and select 'Reinstall macOS' and press 'Continue'.

By doing so, the old High Sierra will be installed on your Mac automatically.

Downgrade Mac OS X (e.g: Downgrade Mac OS X Yosemite to El Capitan)

1. 1. Download the OS X Yosemite installer from Mac App Store.
2. 2. Download the Diskmaker X app to create a bootable USB drive for El Capitan's downgrade.
3. 3. Insert a USB drive into Mac, launch Diskmaker X, and choose OS X Yosemite 10.10. Then the Diskmaker X will do the rest jobs for you.
4. 4. Keep the USB drive inserted into the PC, restart Mac. Hole Option/Alt and chose USB drive in the menu while rebooting Mac.
5. 5. Go to Utilities and select Disk Utility at the Install OS X menu.
6. 6. Select Macintosh HD and choose Erase. Be sure that selected under the Format field is Mac OS Extended (Journaled).
7. 7. Return to Install OS X menu and select Continue to begin the installation of OS X Yosemite.
8. 8. After all these, all you need is to be patient in installing Yosemite on your Mac.

Bonus Tip: Restore Lost Data after Downgrading macOS/Mac OS X(without backups)

This method is for users who have forgotten to back up important data before downgrading Mac OS. And if you lost data after Mac OS reinstallation or downgrading, here is the solution - to restore lost data after Mac OS X downgrading or reinstallation with powerful Mac data recovery software.

EaseUS Mac data recovery software supports to restore whatever you lost in Mac and it's fully compatible with all Mac OS above 10.8

Roll - A - Ball Mac Os Update

And if you happen to lost important data after Mac OS downgrading, let EaseUS Data Recovery Wizard for Mac help you out. Three steps will do all jobs.

Step 1. Select the disk location (it can be an internal HDD/SSD or a removable storage device) where you lost data and files. Click the 'Scan' button.

Step 2. EaseUS Data Recovery Wizard for Mac will immediately scan your selected disk volume and display the scanning results on the left pane.

Step 3. In the scan results, select the file(s) and click the 'Recover Now' button to have them back.

Click here to return to the 'One method of cleaning a Mighty Mouse scroll ball' hint

Wanted to confirm this does work.
We have had a couple mice here that we've tossed in our box o' mice because the scrollball didn't work. Putting pressure on the ball when rolling did dislodge it... for about a week or two. It got to the point that we went back to our other generic mice with scroll wheels, which I still had to use anyway since I have a KVM on my desk and the ((IMO) not-so-)mighty mouse's scroll ball ONLY works when plugged straight into the powerbook.
OK, rantings aside, I did this to a mouse and it's working great so far. I guess see how long this method works. Closest I've tried prior to this was taking a piece of scotch tape, laying it on the table sticky side up, and with the mouse upside down, roll the ball on tape. If you recall, that's always been the recommended way of cleaning the tracking ball on mice, prior to led/laser mice *shudders at the thought*.
It took a few times before I could get the tape to feed in correctly. Like the author, nothing noticeable was on the tape. I was able to slowly rotate the tape around so I could move the tape in all directions. I was able to do this, moving it back and forth and rotating around (was able to go 180º in this time) for about 30 seconds before the tape started to rip and I had to feed it out.

I find a sightly wet finger works the best.
Dip your finger in water, roll it over the ball, and your mighty mouse will be back to work in a few seconds. No need to unplug, no need to dry. (just don't pour water on it.)
---
A completely SANE Canadian.

Most importantly, make sure your three-year-old doesn't drool on it.

Lately I've found a good way to clean the ball, and now I do it every week or so to keep it healthy:
Take a wet wipe and moisten the ball a little, around it (roll and wipe), than place the mouse upside down on a piece of paper, that the ball will touch the paper, and gently roll the ball on that paper. Don't do it too hard because you might break something inside or disform the ball, but you'll see lines of dirt on the paper.
Now it'll be fine!

to add, that with the same wetwipe - you can clean the rest of the mouse, from the rest of day to day dirt... :)

I found that returning it worked well.
By the end mine wasn't scrolling in either direction, tried cleaning it, did nothing, just returned it and got a cheap $5 optical mouse with a scroll wheel.

I am a big fan of blu tac it cleans my keybord and I have used it to my Mighty Mouse scroll ball. it works fine just get a bit and and dab it on the ball jobs done.

blue-tack did the trick - well actually it was Patafix! So frustrating when you can only scroll in one direction :)

Roll - A - Ball Mac Os Download

Thank you, thank you, thank you!!! Your tape 'thing' did the trick. It was not easy to do. But, once I got the tape threaded through; it dislodged big clumps of gunk. Afterwards, I wiped the scroll ball down with alcohol; and now my mouse works fine! Thanks, again!!!

Thanks - my scroll wheel would not work in one direction, but the wet finger trick worked great!

i use some rubbing alcohol on a cotton pad and really roll it around.

This was sent in by Anonymous as a hint, but it belongs here as another solution to the same problem... I am the proud owner of an Apple Wireless Mighty Mouse, and while so far it's treated me well, one problem has persisted for a long time - the scroll ball sometimes ceases to scroll at all. It was so frustrating, and I tried every remedy I could think of, i.e. canned air, dry/wet cloth, alcohol and the like, yet nothing worked for more than an hour or so. I was just about ready to just buy a new mouse when a friend mentioned to me how he cleans the little trackball on his Blackberry - Printer paper.
It may sound strange, but it's the surprising miracle cure for a sticky Mighty Mouse scroll ball. Here's how to go about the procedure:

1. Find a completely blank, completely clean sheet of ordinary white printer paper. Any brand will do.
2. Lay the paper on any hard, flat surface. Unplug the mouse (or turn it off, in the case of wireless MM users), turn it upside down, and make sure the ball can still roll somewhat freely.
3. Press the scroll ball firmly against the sheet of paper, making sure that is the ONLY part of the mouse that touches the paper, and vigorously rub in all directions (up/down, side to side, figure eights, spirals, all that jazz) for one to three minutes. I recommend at least 90 seconds if the ball won't scroll at all in at least one direction, three or more minutes of it just won't budge, period.
4. Reconnect the mouse and test the scrolling by opening anything that has both a horizontal and vertical scroll bar, like iTunes. If it still feels like it's grinding or if it still won't scroll, repeat steps 2 and 3 until you get the desired result.

And there you go! You just protected your $40+ investment with an ordinary piece of paper! I haven't tested this method.
-rob.

Roll - A - Ball Mac Os X

Roll - A - Ball Mac Os Catalina

I tried the alcohol and it did not work for me. I tried the printer paper and it worked. Thanks a lot.