Sidecar from MacBook to iMac

Tom1330 wrote:

Hi there, as my original question says, my iMac can sidecar to my MacBook Pro M1 so can use my MacBook as secondary display, but it doesn't give me the option to do it the other way. Meaning using my iMac as a secondary display for MacBook Pro M1.

FWIW, your 2015 iMac is too old to act as an AirPlay receiver. So is mine.

Hello Tom1330,

Sidecar is a feature between iPad and Mac as outlined here: Use an iPad as a second display for a Mac - Apple Support

If you can share the steps you're using to use your Mac as a display for your iMac the community may be able to better facilitate an answer.

Best regards.

Tom1330,

Got it. What you're referring to is called target display mode, which does allow some iMac models to be used as an external display. Check out this link for compatibility, as it varies by model and software version: Use your iMac as a display with target display mode - Apple Support

"The following older iMac models can be used as an external display when plugged into another older Mac model.

iMac models introduced in 2011, 2012, 2013, and mid 2014

To use any of these iMac models as an external display:

• The iMac used as a display must have macOS High Sierra or earlier installed.
• The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed.
• The cable connecting the two Mac computers must be a Thunderbolt  or Thunderbolt 2  cable.

24-inch and 27-inch iMac models introduced in 2009 and 2010

To use any of these iMac models as an external display:

• The iMac used as a display must have macOS High Sierra or earlier installed.
• The other Mac that you're connecting it to must have been introduced in 2019 or earlier and have macOS Catalina or earlier installed.
• The cable connecting the two Mac computers must be a Mini DisplayPort  cable."

Best wishes.