Hi homer214,
Thanks for reaching out in Apple Support Communities. I understand that you're seeing an error when you're trying to transfer files from your Windows 10 PC to your iMac running macOS High Sierra using Migration Assistant. I know how important it is to transfer your data to a new device and I'd like to help. I'd recommend verifying that you've followed all steps to move data from your PC to your Mac:
Move your data from a Windows PC to your Mac
If so, use the sections below to troubleshoot further:
If the steps above don’t work as you expect, try these options.
Quit other Windows apps
Use these steps to make sure that no other apps are open while you migrate:
- Press Alt-Tab to choose an open application.
- Press Alt-F4 to quit the selected application.
Check your network connection
Does your PC appear in the Setup Assistant or Migration Assistant window on your Mac? If not, make sure that the computers are connected to the same network. You can create an isolated network if you connect a single Ethernet cable between your Mac and PC.
If Migration Assistant still doesn’t show your PC, try to turn off any Firewall software on your PC. It might block network ports that Windows Migration Assistant needs to work. After migration completes, you can turn on your Firewall software.
Turn off antivirus software
If Migration Assistant doesn’t open on your PC, turn off any antivirus software on your PC. Then try to open Migration Assistant again. After migration completes, you can turn on your antivirus software.
If your PC isn’t compatible with Migration Assistant
There are other options you can use to transfer your data. For example, you can use an external drive or file sharing to manually copy important data to your Mac.
Let me know what you find.
Best Regards.