This computer's hostname "Jeffs-iMac.local" is already in use on this network

[JeffL]

The above message appeared on the screen of my iMac for the first time yesterday. I've googled the problem and although there are plenty of discussions on the subject, as a non-techie I am unsure what I should do. I have had my MBA M1 on my desk next to the iMac since I bought it many months ago so I can't see that that has anything to do with this message appearing now on the iMac. Is there anything I need to do or should I ignore the message. (Note, I do have a new 24" iMac on order which should be delivered during the next few weeks). If there is something I should do, could someone please give me the idiot's guide step by step. Thanks.

 

[Slydude]

The physical proximity of the two computers is irrelevant as long as they are on the same network. If you copied your setup from one computer to another, they would share the same user accounts and other settings, such as the computer's name.

Open the Sharing preference pane on both computers and check the names that appear there. If both computers have the same name, click the edit button and change one of them.

 

[JeffL]

The physical proximity of the two computers is irrelevant as long as they are on the same network. If you copied your setup from one computer to another, they would share the same user accounts and other settings, such as the computer's name.

Open the Sharing preference pane on both computers and check the names that appear there. If both computers have the same name, click the edit button and change one of them.

Just looked and In Settings/Share on the iMac it is Jeffs-iMac-2.local on the MBA it is MacBook-Air.local

 

[Slydude]

In that case, my initial thought wasn't 100% correct. I've seen this before and had it happen to me, IIRC. I don't quite remember how I fixed it. I'm sure we can fix this.

 

[JeffL]

In that case, my initial thought wasn't 100% correct. I've seen this before and had it happen to me, IIRC. I don't quite remember how I fixed it. I'm sure we can fix this.

Thanks Slydude, looking forward to more ideas coming

 

[chscag]

Just looked and In Settings/Share on the iMac it is Jeffs-iMac-2.local on the MBA it is MacBook-Air.local

There's definitely something out of whack there. The Settings/Share on your iMac (Jeffs-iMac-2.local) does not jive with the error your received (Jeffs-iMac-local). Appears to be two different iMacs?

My suggestion is to kill the sharing on all the machines and start over. I'm not sure if those settings are easily removed. You may have to do some digging. Slydude will probably figure it out for you.

 

[MacInWin]

The network sharing has renamed his machine to "Jeffs-iMac-2.local" to avoid conflict with what it thinks is "Jeffs-iMac.local." Not two machines, the same one, but somehow logged into the local area net twice. I've seen it when a machine is logged in by WiFi and then connected by Ethernet. Each interface gets a separate IP, but then sharing thinks that at one IP is a machine with the same name as at the other IP and renames itself to avoid the conflict it thinks is there. What I have done is log out of both (turn off WiFi, disconnect Ethernet), then rename back to original and then turn on WiFi again and plug in the Ethernet.

 

[JeffL]

The network sharing has renamed his machine to "Jeffs-iMac-2.local" to avoid conflict with what it thinks is "Jeffs-iMac.local." Not two machines, the same one, but somehow logged into the local area net twice. I've seen it when a machine is logged in by WiFi and then connected by Ethernet. Each interface gets a separate IP, but then sharing thinks that at one IP is a machine with the same name as at the other IP and renames itself to avoid the conflict it thinks is there. What I have done is log out of both (turn off WiFi, disconnect Ethernet), then rename back to original and then turn on WiFi again and plug in the Ethernet.

OK I'll try that. FYI the only thing being shared between the iMac and the MBA is my printer but I have just un-shared it. See photo attached and a photo of the original message which I should have uploaded originally.

 

[MacInWin]

If you open System Preferences, then Sharing and unlock it, you should see something like this:



Now if you click on Edit... you get this:


And if you click on the "?" a help screen opens up with this (I added the red oval around the pertinent part):



So, if your system appears to be two different machines to the network, it gets renamed with the number added.

 

[Slydude]

Thanks for that description, Jake. It would seem to match what I remember about the few times I've had this problem.

@JeffL If Jake's suggestion doesn't fix your problem, try these tips and see if they help Tackle a Mac's name changing with sequential numbers

 

[IWT]

@JeffL

It may be irrelevant, but in your first attached image (left one), should you not have Printer Sharing ticked?

Ian

 

[JeffL]

@JeffL

It may be irrelevant, but in your first attached image (left one), should you not have Printer Sharing ticked?

Ian

Hi Ian. I did have printer sharing ticked but I unticked it as a temporary measure in case that was part of the problem.

 

[JeffL]

Thanks guys. I've done the procedure suggested by Jake so will just have to wait and see if that has sorted the problem long term.