I have an iMac (27-inch, Late 2012) and after updating to MacOs Catalina 10.15.6 (19G73) from previous version, the target display mode doesn't work.
Clicking "command + F22" does not work anymore.
Could anyone help me on this?
Thanks in advance.
iMac 27″, macOS 10.15
Resseting NVRAM like rKaufmann87 said works for me.
It was working well with macOS Mojave 10.15.5. It doesn't work after updating to the last version.
I am experiencing the same issue. My 27" is the late 2011 version and up until I completed the 10.15.6 update, TDM was working perfectly. HELP!?
And to be clear, I am pushing Command+F2
Disconnect all connecting cables and reset the NVRAM on both machines. If it still does not work, you may want to consider getting an external display. TDM has not been supported for some years now.
NVRAM Reset instructions.
Is the Late 2012 the one you want to use as an extra display? If so, you will need to downgrade its OS to 10.13 or less. See:
Use your iMac as a display with target display mode - Apple Support
specifically this part:
Target display mode not working after updating to MacOS 10.15.6 (19G73)
