LockDown Browser Screenshot Disabled on Mac (Cmd-Shift-3/4/5 Blocked)

Last updated 2026-05-02 · LDBypass Editorial

What's blocked

• Cmd-Shift-3 (full screen screenshot to clipboard or file).
• Cmd-Shift-4 (selection screenshot).
• Cmd-Shift-4 then space (window screenshot).
• Cmd-Shift-5 (screenshot toolbar with screen recording).
• Third-party screenshot tools that bind these keys (CleanShot, Snagit, Skitch, etc.).
• Custom keyboard shortcuts that map to screenshot.

What happens if you try

Attempting any of the screenshot keystrokes during the exam:

1. The keystroke is intercepted by LDB before macOS's screenshot service receives it.
2. No screenshot is captured.
3. The attempt is logged in the Monitor recording timeline as a "screen capture attempt" event.
4. Your instructor sees the attempt when reviewing the recording.
5. The exam continues normally.

How the block is implemented

LDB hooks into macOS's keyboard event system at the application-foreground level. When the kiosk-mode app is active:

• Cmd-Shift-3/4/5 keystrokes route to LDB instead of the screenshot service.
• LDB checks if it's in active exam mode → discards the keystroke + logs the attempt.
• The macOS screenshot service never sees the request.

This works at the kiosk-mode-app level, which is why third-party tools that rebind these keys are also blocked - they're intercepted before reaching the rebinding tool.

Why instructors disable screenshots

• Prevents distributing exam content to other students.
• Prevents capturing answer keys (when feedback is shown after submitting).
• Prevents documenting your work to support cheating allegations.
• Prevents pasting screenshots to ChatGPT / Claude for help.

What screenshots LDB does take (and uploads)

LDB takes screenshots of YOUR screen as part of Monitor:

• Periodic screen captures every ~30 seconds + at page transitions.
• Full screen, native resolution, JPEG-compressed.
• Uploaded to Respondus servers as part of the recording.
• Reviewable by your instructor.

The asymmetry: Respondus captures your screen but you can't capture theirs. By design.

What still works

If you legitimately need to capture an error

Some scenarios where capturing the LDB error is genuinely useful:

• You hit a numbered error code that prevents launching.
• The exam interface is broken (LMS-side bug, not LDB).
• You want to document a technical failure for academic-integrity defense.

Workaround: photograph the screen with your phone. The Monitor recording captures you doing it - instructors generally accept this when accompanied by an explanation. The phone screenshot is retained by you (not flagged unless you also use the phone for cheating during the exam).

What screenshot attempts look like in the Monitor recording

From the instructor's review interface:

• A timeline marker labeled "Screen capture attempt" at the timestamp.
• The keystroke is not visible (LDB intercepted it), but the attempt is logged metadata.
• Instructors typically don't penalise individual attempts - they look at patterns. One accidental Cmd-Shift-4 during the exam is forgivable; ten attempts in a row look intentional.