Can I Still Use My Old Mac After Using Migration Assistant?
Yes, you can still use your old Mac after using Migration Assistant.
No matter which way you use Migration Assistant to transfer files to your new Mac. Mac Migration Assistant copies your files over to your new Mac.
No file is changed or deleted on your old Mac. So, you can continue to use your old Mac as before after running Migration Assistant.
And this doesn’t change if your new Mac is a M1 Mac, MacBook Pro or MacBook Air. Your old Mac stays the same.
Can You Use Your Old Mac While Migration Assistant Is Running?
The answer depends on the Migration method you use. Run Migration Assistant over cable and no you can’t use your old Mac.
When you open Migration Assistant and use over WIFI. It’s not possible to use your old Mac while Migration Assistant is running. Migration Assistant closes all apps on your old Mac and only runs Migration Assistant.
Run Migration Assistant using a Mac Time Machine backup. And your old Mac is completely free for you to use while Migration Assistant is running.

Can I Use Old Mac While Migration Assistant Is Running Over Cable?
When you run the Migration Assistant app over cable. Your Mac transfer is over Gb Ethernet cable or Thunderbolt USB cable.
You’ll need to put your old Mac into Target Disk Mode to transfer files.
This means your old Mac acts like an external hard drive to your new Mac.
When set up in Target Disk Mode you can’t use your old Mac while Migration Assistant runs.
Can I Use Old Mac While Migration Assistant Is Running Over WIFI?
No. Use Migration Assistant to transfer files Mac to Mac over WIFI, and you can’t use your old Mac while Migration Assistant is running.
Migration Assistant on your old Mac closes down all other applications. And of course while you’re running Migration Assistant over WIFI the WIFI will be busy.
The old Mac’s internal Macintosh HD drive will be busy sending data.
Can I Use Old Mac While Migration Assistant Is Running With A Time Machine Backup?
After you’ve taken the Time Machine backup of your old Mac. Your old Mac computer plays no part in your migration process.
You put your external drive – external SSD (Solid State Drive). Or external hard drive onto your new Mac computer. Launch Migration Assistant on your new Mac and point it to your external drive.
Migration Assistant transfers files using your Mac Time Machine backup. This leaves your old Mac computer completely free for you to use.
And yes, in this case you can still use your old Mac while Migration Assistant is running on your new Mac.

Other Useful Migration Assistant Information To Know
Migration Assistant Does Not Transfer Old Mac OS
With all the latest Mac OS x operating systems like Mojave, Big Sur and Monterey. Your Mac comes factory installed with an operating system.
You then start your new Mac and use Setup Assistant. In Setup Assistant you set your new Mac’s system preference. Enter your Apple id and iCloud drive information.
It’s best to complete this before running Migration Assistant.
Log into your new Mac when it restarts and update your OS x if there is an update waiting.
You do all this before you launch Migration Assistant on your new Mac. And start your file transfer from your old Mac.
Migration Assistant Will Copy Your Apps And User Files From Your Old Mac To New
Migration Assistant works out which apps your new MacOS supports. And which of your Mac applications no longer run because Apple replaced them.
Migration Assistant copies over your user account. It searches the home folder of your user account and copies all the files it finds. And this includes your documents, music, calendar entries, contacts.
You can copy over other files and folder’s Migration Assistant finds. Along with your old Mac’s operating system (OS x) preferences and network settings.
Windows Migration Assistant Is For Windows PCs
This app is a close cousin of Migration Assistant. You can download this app from the Apple App Store and use it to transfer your user files from a Windows PC to a Mac.
In Closing
And now you know the answer to your question. Can I still use old mac after Migration Assistant? And know there are ways you can use your old Mac while Migration Assistant is running.
While you’re here do take a look at the other Migration Assistant related articles on the site.
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