LockDown Browser Sidecar (iPad as Display) on Mac - Why It's Blocked
Why Sidecar is blocked
Sidecar implements iPad-as-display via macOS's standard CGDisplay system. From the operating system's perspective, the iPad is a registered display alongside your built-in screen. CGDisplayActiveDisplayCount returns 2.
This is identical to how an HDMI monitor would register. LDB doesn't differentiate; both trigger the multi-display block.
The privacy reason: Monitor records what the camera sees (your face + laptop screen), not adjacent screens. A second display, including an iPad-Sidecar, is outside the camera's view and could display reference materials.
How to disable Sidecar
- System Settings → Displays.
- In the Displays list, find your iPad (it shows up as e.g. "iPad Pro").
- Click the gear icon next to the iPad.
- Click "Disconnect".
- Wait 5 seconds for the connection to fully terminate.
- Verify only your built-in display is listed.
- Launch LDB.
Alternative path:
- On iPad: open Control Center → Sidecar widget → Disconnect.
- Same result.
Sidecar vs. Universal Control vs. Continuity Camera - different products, different rules
| Feature | iPad as... | LDB blocks? |
|---|---|---|
| Sidecar | Second display | ✓ Yes (CGDisplay registered) |
| Universal Control | Cursor extension (still iPad's own display) | ✗ No (not a CGDisplay on Mac) |
| Continuity Camera | Webcam input | ✗ No (camera, not display) |
| iPhone Mirroring (Sequoia 15+) | Mirror iPhone screen on Mac | ✓ Yes (treated as display) |
Edge case: iPad just sitting there next to your laptop
If the iPad is awake but NOT in Sidecar mode, it's not registered to macOS's display system. LDB can't detect a non-Sidecar iPad. However:
- Monitor records the camera frame. If your iPad is in the camera's view, it's recorded.
- If the iPad displays reference content visible to the camera, it's flagged for instructor review.
- Most universities consider any non-exam device in frame as "suspicious" regardless of whether it's technically a "display".
Practical advice: keep secondary devices out of the camera view, off, or in a different room during proctored exams.
Re-enabling Sidecar after the exam
After exam submit + LDB exits:
- System Settings → Displays.
- Click "Add Display" or "Mirror or extend to ..." dropdown.
- Select your iPad.
- Sidecar reconnects.
Or via Control Center → Screen Mirroring → select iPad.
Workflow tip: don't use Sidecar on exam day
If your daily workflow uses Sidecar heavily (graphic design, programming with iPad as second screen), build a habit of disabling Sidecar at the start of any exam-day study session - this way you're not scrambling 10 minutes before the exam to disconnect.
Frequently asked questions
Can I use Sidecar in display-mirror mode (same content) instead of extend?
No - both modes register the iPad as a CGDisplay. LDB blocks both equally.
My iPad shows the Sidecar disconnect option but it doesn't work.
Sometimes Sidecar gets stuck. Reboot your Mac to fully release the connection. Also reboot your iPad if Sidecar still appears in the iPad's Control Center after disconnect.
If I use the iPad app for the exam (not Sidecar), is that OK?
LDB on iPad is a separate app from LDB on Mac, with different feature support. Your university's Respondus Dashboard configuration determines whether iPad LDB is acceptable for your specific exam. Check with your instructor.