I have been struggling with trying to make my iMac 2013 a 2nd monitor for my MacBook Pro.
I used the cable and the adapter.
formatted and downgraded the iMac to El Capitan
tested the cables and the adapter using the target disk drive and worked
tried other MacBook Pro that I have but with same results
and still no luck
iMac 27″, macOS 10.15
Which exact cable(s)
Target display mode requires macOS High Sierra or earlier on the iMac used as the external display. It does not work with macOS Mojave or later.
What year is the MacBook Pro?
Use your iMac as a display with target display mode - Apple Support
"You can connect any of these older iMac models to another Mac from 2019 or earlier"
Is it an Apple Keyboard on the iMac?
You might have to start a new topic to get more help, most won't look at already solved ones.
MacBook Pro is 2019
I have the thunderbolt cable 2 m and the thunderbolt adapter
Apple Keyboard on the iMac - yes
I take my post got mistakenly marked solved???
You’re right.
it’s not solved yet.
using the iMac 2013 as a 2nd monitor for the MacBook Pro
