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Sidecar Not Connecting iPad to Mac: “The iCloud account does not use two-factor authentication” — Fixed by signing out

I opened my MacBook at the office as usual and tried to use my iPad as an external display. Then this message appeared and I could not connect:

The iCloud account does not use two-factor authentication.

(Japanese UI equivalent: 「iCloud アカウントは二要素認証を使用していません。」)

I am not sure why it showed up all of a sudden. The only change I remember is changing my Apple Account password. I had re-signed in to the devices I could think of after that.

Even so, something around Sidecar may have been left in a bad state.

This post walks through common Apple Support–style troubleshooting and what finally worked on my setup.

Environment

ItemDetailsOS
MacMacBook Pro (Apple M1 Pro)Tahoe Version 26.3.1 (a)
iPadiPad Air (4th generation)26.3.1 (a)

OS versions match what the devices showed at the time.

What I tried first (typical official guidance)

For Sidecar and Continuity, Apple documents prerequisites and checks in Use Sidecar on your Mac and related articles. I went through them in roughly this order.

1. Cables and connections

  • I was on USB-C, so I swapped cables and tried different ports.
  • For wireless Sidecar, I confirmed both devices were on the same Wi-Fi.

2. Confirm two-factor authentication (2FA)

The message points at two-factor authentication for your Apple ID.

  • On each device: Settings → your name (Apple Account) → Sign-In & Security (names vary by OS) and verify Two-Factor Authentication is on.

On my devices, 2FA was already on, but Sidecar still behaved as if something was stale.

3. Same Apple Account on both devices

I confirmed Mac and iPad were signed in to the same Apple Account.

4. Wi-Fi, Bluetooth, and Handoff

  • Toggle Bluetooth off and on.
  • Check Handoff on the Mac (e.g. General → AirDrop & Handoff).
  • Confirm Internet Sharing is not interfering (often listed as a requirement in Apple’s docs).

5. Restart

I restarted both the Mac and the iPad. Simple, but often effective for connectivity.

6. Software updates

I checked for macOS and iPadOS updates and kept them reasonably current.

None of that restored Sidecar for me. The error stayed and the iPad would not work as a display.

What fixed it: sign out on both, then sign in again

The step that worked was signing out of my Apple Account on both the MacBook and the iPad, then signing in again.

  1. Mac: Sign out of your Apple Account (follow prompts if you need to keep copies of data).
  2. iPad: Sign out the same way.
  3. Sign back in on one device, then the other, with the same account.

Signing out can trigger iCloud data and on-device content prompts; read Apple’s guidance and back up anything you cannot afford to lose.

After that, Sidecar recognized the iPad as an external display again and the error message stopped.

Summary

  • “The iCloud account does not use two-factor authentication.” appeared even though 2FA was enabled; Sidecar stopped working.
  • Cable checks, 2FA verification, same Apple ID, connectivity, restarts, and updates did not fix it in my case.
  • Signing out on both Mac and iPad, then signing back in restored the connection.

I cannot prove the password change alone caused it, but a mismatch between local sign-in state and Apple’s security settings can explain misleading messages. If you see the same error, add this to your list of things to try.

References