My iMac's computer name keeps changing automatically after Yosemite upgrade

Boot into the Recovery Drive. Run Disk First Aid on your internal drive.

Boot into the Recovery Drive by holding down Command R when restarting.

Open Disk Utility

Run First Aid on your internal drive, Macintosh HD

Quit Disk Utility

MORE INFO:

https://support.apple.com/en-us/HT201314

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Remove any accents, apostrophes or special characters in Computer Name.

Check to see if the Computer Name(as seen in the Sharing Preference Pane), Local Host Name and Host Name are the same. The Local Host Name and the Host Name, which is often it's fully qualified name if

on a company network (such as computer.example.com). Often these are identical but they can be different. More Info

Open the Terminal application in Applications/Utilities. Run these three

commands:

sudo scutil --get ComputerName

sudo scutil --get LocalHostName

sudo scutil --get HostName

If the names are different you can try changing using these commands. Copy/paste usually works, but you might need to type out the commands.

sudo scutil --set ComputerName "newname"

sudo scutil --set LocalHostName "newname"

sudo scutil --set HostName "newname"

Reference:

http://osxdaily.com/2012/10/24/set-the-hostname-computer-name-and-bonjour-name-s eparately-in-os-x/

http://stackoverflow.com/questions/40027067/cannot-resolve-local-hostname-after- upgrading-to-macos-sierra

http://osxdaily.com/2010/09/06/change-your-mac-hostname-via-terminal/

I have seen other reports of this behavior. You need to report it to Apple Feedback so it can be logged and put in the queue to be fixed.

http://www.apple.com/feedback/macosx.html

Normally, you see this if you have other volumes on your network with the same name.

If you create a new User in System Preferences > Users & Groups, do you see the same naming as you do in your User?

CREATE A NEW USER

Go to System Preferences --> Create a New User in Users & Groups

Switch to the New User by logging out under the Apple in the Menu Bar.

If the problem goes away, it's a problem in your User's folder.

If the problem exists in the new User, this indicates a problem at the base level. This would indicate it could be a bug.

I have exactly the same problem with my late 2012 iMac.

Currently mine has gone to (6). I have renamed it in the weekend, but as theshadow82 says, it does not work and simply starts counting up again.

If you have any more details on this issue, I am very interested in how to solve it.

"Back to my Mac" on your iCloud in System Preferences is the culprit.

Not sure if we can find a workaround. We'll wait for Apple to correct that issue.

I did sign out and chose "Delete" on every pop up then signed back in. They just came back.

Solution:

OS X Yosemite: If Back to My Mac doesn’t work

If you have AirPort Base Station (Express, Extreme, or Time Capsule), open AirPort Utility and delete all Apple ID entries for Back to My Mac.

Click Apply to restart the AirPort

Re-add your Apple ID

Restart again

It should fix it. The problem lies to AirPort's old settings.

This does not correct the problem, my Airport Extreme has no Back to my Mac info populated (I used VPN with OSX Server for that)

2 out of my five Macs in my network have exhibited this issue since Yosemite upgrade except for my server, which remains on all the time, makes sense since it never has to rejoin the network. The iMac as does go to sleep but never "leaves" the network, where the three laptops do. but only the older 13" MBPros seem to be affected.

I tried implementing DNS on my server to force them to remain but the issue still occured.

13" MBPro 2010 (Lennon) -> increments ex. Lennon (3)

13" MBPro 2010 (Morrison) -> increments

15" MBPro 2013 (Cooper) -> Computer name stable, leaves network VERY frequently

iMac (Joplin) Computer name stable

Mac Mini (Hendrix) Computer name stable

I just disabled the "back to my mac" settings on both base stations and in the iCloud settings on both my 2012 iMac and 2009 MacBook Pro. Everything seems to be holding stable for now. I lose my Sonos system immediately when the Computer Name changes.

I had the same issue with my mid-2012 MBA. Back to my mac has always been disabled. I also have a Time Capsule. In addition to the computer renaming, I noticed unstable performance (I was having to force quit applications much more often.) I restored from a backup taken before Yosemite and decided to wait it out a bit.

I just submitted a bug report also. I am not using "Back to my Mac" but am still seeing my name increment on my Late 2011 MBP. Plus, it is showing all of the older iterations of the name under "Shared" as if they were other devices on my network.

Have had the same issue with an iMac and MacBook Pro, both with Yosemite (MacBook upgraded from the Yosemite public beta). Both previously had Mavericks, and at one time or another would have had both Ethernet cable and Wifi on. This issue has only occurred since the upgrade to Yosemite. I do not use iCloud, so I believe that may be irrelevant and merely coincidental.

The solution provided by an Apple Care rep seems to have resolved the issue. Has stuck now on both machines for the last few hours. Time will tell for certain, but here's what we did:

- in System Preferences > Sharing, remove the (2) [or whatever is extra; mine was iMac (2), so I removed the (2)

- exit Preferences

- shutdown

- restart machine in Recovery mode (machine off, press and hold Command + R, power on, when Apple logo appears release keys)

- may take a few minutes to boot (depends on machine generation/speed, RAM and such)

- open Disk Utility

- select the OS disk (mine was Macintosh HD; selected the 'indented' item)

- run Verify Disk Permissions

- when finished run Repair Disk Permissions

- restart

On the MacBook I tried turning on Wifi and so far so good.

Banish the deux!

Thank you for this. I'll see how it holds up for the day.

On a related note, my iPhone 6 is still trying to connect to my iMac (9) and resetting the network settings does nothing to fix this. Now my iPhone won't sync to the iMac since it no longer recognizes it. When I tell the phone to trust the computer it fails.

Any suggestions?

Ok,

I tried this and so far so good! I will keep an eye on it and report back if something changes. I really appreciate you taking the time to post this!

Also, while I was verifying and scanning it said I had some disk errors and repaired my disk also. This made my entire machine run faster. I was experiencing a lot of boot delay which is TOTALLY gone now. It also free'd up about 24 gig of space on my SSD. I checked and it looks like all of my files/apps are still good so that was a nice bonus.

Again..thank you for taking the time to contribute to the community.

Dan

This seems to be working for me too...had several disk permission issues! I'll be switching wifi networks a few times tomorrow...will report success or failure.