Why is a display missing, a switch disabled or a setting unavailable?
Start with the exact symptom: a missing display row, a disabled connection switch, an absent setting, or a displayed error. They have different causes.
In this article
What should I check when a display is missing?
- Confirm that the monitor is powered and the cable, dock, or adapter is connected to the Mac.
- Select the Mac's input on the monitor. Another input can make a display unavailable to macOS even while its cable remains attached.
- Open System Settings → Displays and check whether macOS detects it.
- Close and reopen Radar Display's panel to refresh its presence list.
- If this is a MacBook, open the lid to make the built-in screen available for recovery.
The physical-monitor list is intended for the built-in screen and directly attached physical external displays. It does not list every virtual display, AirPlay destination, or software-created screen. Sidecar iPads have a separate discovery path; use iPad troubleshooting.
Radar Display hides a remembered monitor while it is absent. Its saved record is retained; there is no requirement to rename it or recreate its settings simply because it was unplugged. Two indistinguishable monitors can remain difficult to match correctly after their connections change.
If macOS sees the monitor but Radar Display does not, note the monitor model, connection path, and whether it is an active extended or mirrored display. Send those details with the app and macOS versions.
Why is the connection switch disabled or missing?
Only active display means Radar Display is protecting the last active physical screen. Turn on another usable physical display before trying to disconnect that one. An iPad does not satisfy this guard, and a mirrored secondary screen might not count as another active physical screen.
Disconnect mechanism unavailable on this macOS means Radar Display cannot use the macOS interface required for physical-display disconnection. The physical connection switch can then be absent. Reinstalling a color profile or changing brightness does not supply that interface.
No displays detected. means the current panel has no detected rows. Check the connections and reopen the panel. If the app sends a MacBook back to setup instead of opening controls, check the approved helper connection; that is a separate setup gate.
During a connection change, a progress indicator marks the affected display. Let that operation finish before another attempt.
Why is a setting absent, or why did a change fail?
Radar Display shows controls only when the display is on and the relevant value and capability are available. Common reasons for an absent row include:
| Control | Conditions to check |
|---|---|
| Use as | The display must be active and have applicable role choices. |
| Position | The display must be active, extended, and not main, with an available peer or a saved rule naming an absent peer. |
| Text-size strip or Resolution | Available modes determine which surface appears. A current readable mode and enough usable choices are required. |
| Refresh rate | More than one applicable rate must exist for the current resolution/scaling mode. |
| Rotation | A supported physical external display is required; built-in rotation is intentionally absent. |
| Brightness | macOS must expose usable brightness reading and control. Some external displays expose it only under particular settings. |
| Automatically adjust brightness | Suitable brightness and ambient-sensor capability must be available. |
| True Tone | Radar Display offers the system setting through a supported built-in display card. |
| HDR | HDR support and a readable current state must be known. |
| Preset or Color profile | Usable choices must be available. Preset takes precedence over Color profile. |
| Show Sidebar or Show Touch Bar | A Sidecar session and its control interface must be available. |
| Enable double tap on Apple Pencil | Sidecar preference access must be available and the preference must not be managed. |
| Connection | The connection must be identifiable. An unknown value is omitted. |
After changing the connection or display configuration, reopen the panel. The app rechecks the hardware rather than showing every control on every screen.
Errors under a display identify a failed request for that row. Messages such as macOS refused while… (error [number]) indicate which operation was refused. The error number alone does not prove a specific cable, monitor, or permission fault.
Wait for any operation to finish, then retry the relevant change using an available value. A successful unrelated setting does not clear a failed setting's message. A connection error can disappear when fresh display observations show that the intended state was reached. There is no error-dismiss button, and reselecting a no-op value might not issue a new request.
An Arrangement: error at the bottom of the panel refers to arranging displays. Sleep-control errors belong to the Behavior controls. Use the wording and location to choose the next check.
How do I recover a dark or unreadable screen?
- Open the MacBook lid if applicable.
- Confirm the external monitor's power, cable, and selected Mac input.
- From a working physical screen, open Radar Display and turn the affected display on.
- If its picture is present but unreadable, choose a supported resolution or Rotation → Standard from the working screen. System Settings → Displays is another place to change its mode.
- If the lid policy is involved, choose Closed Lid Mode → Automatic and allow restoration to finish.
Normal quitting attempts to restore disabled physical screens but does not reset their resolution or rotation. A crash or force quit skips restoration. See quit and recover.
What details should I send to support?
Include the exact error, app version, macOS version, Mac model, monitor model, and the connection path: for example, HDMI directly from the Mac or DisplayPort through a named dock. Say whether the monitor is extended, mirrored, on another input, manually switched off, or affected by a closed-lid mode.
For mode problems, include the chosen resolution, refresh rate, rotation, and HDR state if available. For a missing row, say whether System Settings detects the display. For Sidecar, include the iPad model, iPadOS version, reported Wi-Fi/USB session, and whether Apple's own controls work.
Radar Display has no in-app diagnostics export or error-copy button. Record the visible wording accurately. A screenshot from a working display can show where the error appears; avoid including unrelated personal content.