27" Thunderbolt Display to a 14" MacBook Pro M1?

If it is a Thunderbolt Display, you use the Apple ThunderBolt-3 <-> Thunderbolt-2 adapter (US$50). This adapter does not support any other types of displays, even with additional adapters added.

• The Apple Thunderbolt Display lead-in cable has two connectors: Thunderbolt-2 and MagSafe

• The Apple Cinema Display lead-in cable has three connectors: Mini DisplayPort , MagSafe, and USB-A

Lots of users have issues mistaking the very similar Cinema Display for the thunderbolt Display. Did you check the number of cables in the lead-in cord, and does it, in fact have two and not three connectors as I described above?

The Mac uses a system that reminds me of “Plug and play” to determine what display is connected, and what its capabilities are.

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.

This query is only sent at certain times:

• at startup

• at wake from sleep — so momentarily sleeping and waking your Mac may work

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)

so try doing some of those things and see if the display comes alive.

Other readers have reported that once any confusion about whether theirs was

• the Cinema Display with three connectors (counting MagSafe as one of the three) or

• the Thunderbolt Display with two connectors (counting MagSafe as one of the two)

... the Apple Thunderbolt-3 <-> ThunderBolt-2 adapter worked fine for the Thunderbolt Display, and their displays are working.

If yours is not working and you have swapped things around a bit, perhaps the adapter is defective.

To the best of our knowledge here, that is supported.

Since it is new, and you get 90 days of free telephone support, I recommend you ask Apple support to investigate. If they cannot provide a solution, be polite and professional, and ask for a Specialist to contact you for further investigation or filing a Bug Report.

Official Apple Support

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