I've had no issues in the past displaying my MacBook pro screen onto my iMac for larger screen use. Ever since I did the new update I cannot get the display to mirror, yet I still have to option to click my iMac to display. I get the warning message "Could not connect to "Ali's iMac"". This is also when the thunderbolt cable is plugged into both.
[Re-Titled by Moderator]
iMac 24″, macOS 15.2
Target display mode is dead technology. It is no longer supported in hardware nor in software since the release of retina Macs and macOS 11 Big Sur.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution - Luna Display or Duet Display - though the performance of those options is limited. They are only suited for uses where there will be limited motion and where lag time is not an issue, such as for application tool palettes.
Target display mode is dead technology. It is no longer supported in hardware nor in software since the release of retina Macs and macOS 11 Big Sur.
Please see: Use your iMac as a display with target display mode - Apple Support
Per the link above:
• Your target iMac (monitor) must be using macOS High Sierra 10.13.6 or earlier.
• In all cases the source Mac that you're connecting FROM must have been introduced in 2019 or earlier and have macOS 10.15 Catalina or earlier installed.
You might consider a third-party solution - Luna Display or Duet Display - though the performance of those options is limited. They are only suited for uses where there will be limited motion and where lag time is not an issue, such as for application tool palettes.
Are you trying to use Target Display Mode (which none of the 24” Apple Silicon iMacs support), or AirPlay to Mac with such an iMac set up to be an AirPlay Receiver?
Unable to mirror MacBook Pro screen to iMac after software update
