SideMiniTroubleshooting
Sidecar stopped working after a macOS update: what to check
A macOS update is the most common reason a working Sidecar setup stops working. Usually nothing is broken: the update reset a setting, signed you out of something, or left a service that has not come back yet. Work through these in order before you assume Apple removed the feature.
Restart both devices, properly
Not sleep and wake: a full restart on the Mac and on the iPad. Sidecar depends on background services that occasionally do not come back after an update, and they are not restartable by hand in any supported way.
Give the Mac two or three minutes after login before judging. Immediately after an update, macOS is busy re-indexing and re-registering services, and Sidecar is not first in the queue.
The settings updates like to reset
- Handoff. System Settings → General → AirDrop & Handoff. It gets switched off by updates more than anything else, and Sidecar will not work without it.
- Bluetooth. On both devices, even if you connect over a cable.
- Apple Account. Confirm both devices still show the same account and that two-factor authentication is on. A password change signs one device out quietly.
- Personal Hotspot. An update can re-enable internet sharing, which blocks Sidecar outright.
Check the requirements did not move
Apple has raised Sidecar’s requirements before, and the device list is the only authority worth trusting. Read it after any major upgrade rather than assuming last year’s answer still holds.
A major upgrade can also change menu names. Screen Mirroring in Control Center is the current path; older releases put it in the AirPlay menu or a dedicated Sidecar pane.
If the Mac has no monitor
This one is not an update problem and never was. A Mac with no display attached cannot host a Sidecar session: it connects, then drops a few seconds later, every time. If your setup worked before the update, something was providing a display and now is not, usually a dummy plug that came loose or an app that created a virtual one. See using a Mac mini without a monitor.
When a tool that automates Sidecar breaks
Automation tools, SideMini included, talk to interfaces Apple does not document. A major macOS update can change them, and when that happens the honest behaviour is to say so rather than fail silently. SideMini reports the problem in its menu and its Doctor pane, keeps every other feature working, and a fix ships as a free 1.x update.
Plain Sidecar, started by hand, is unaffected by any of that. If manual connection works and only the automation is broken, that is the situation you are in.