LockDown Browser Won't Open: The Fix (And What to Do Instead)
TL;DR
LockDown Browser refuses to start when it detects banned software, VMs, multi-monitor setups, or network issues. The fix is closing the flagged software — though sometimes the flagged software is something you didn't realize was running.
If LockDown Browser won't open ten minutes before your exam, the message often doesn't explain what it found. Here's the actual ranking of causes.
Cause 1: Banned process running (most common)
Screen recorders, VMs, remote-desktop tools, certain macro programs. Quit them all. On Windows, check the system tray; on macOS, check the menu bar.
Cause 2: Multi-monitor setup
Disconnect external displays before launching. iPad / iPhone in Sidecar mode counts as a second monitor.
Cause 3: VM detected
VirtualBox, VMware, Parallels services running in the background even if no VM is active. Quit the host services from your system tray.
Cause 4: Network or telemetry blocked
Corporate or school firewalls sometimes block Respondus's telemetry endpoints. Connect to a personal network if possible.
Cause 5: OS update mismatch
Major macOS or Windows updates sometimes break the LockDown Browser version your school has deployed. Updating LockDown Browser itself often fixes it.
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Sign up nowFrequently asked questions
What if I can't figure out which process is blocking it?
Restart the machine, open nothing, then launch LockDown Browser. If that works, the culprit was something running before. Add software back one at a time on your next test launch.
Will an OS-level overlay like Lockdownify cause this?
No. Lockdownify isn't categorized as a screen recorder, VM, or remote-desktop tool. LockDown Browser's process scanner doesn't flag it.
Will Lockdownify get me caught?
No. Lockdownify is filtered out of every screen-capture pipeline at the operating-system level — before a single pixel is ever encoded. LockDown Browser, Honorlock, Proctorio, Zoom, Teams, and Meet all read the same OS frame buffer, and Lockdownify is excluded from it. We re-test against every major proctoring tool weekly. If you ever do get flagged, we refund your subscription and reimburse the exam fee.
What platforms does Lockdownify support?
macOS 13 Ventura and later, and Windows 10 and 11. Both desktop apps ship today.
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