Second Monitor, Dual Screen and External Display: Will They Get Your Online Exam Cancelled?

You must disconnect every display except the one you are testing on. Proctoring software reads how many displays your operating system reports, and a second monitor that is switched off but still plugged in is usually still reported. The exam will refuse to launch, and if a display connects partway through a session, that is treated as a serious violation rather than an oversight.

This is the single most common launch failure among IT professionals, for the obvious reason that multi-monitor setups are normal in this line of work.

Why turning it off does not work

Powering a monitor off changes nothing from the operating system's perspective. The display is still enumerated, still has a resolution, and still appears in display settings. The check is looking at that list, not at which screens are illuminated.

The same applies to extending or duplicating displays in software, and to setting a second screen to show nothing. The connection is what matters.

Disconnect the cable at one end. That is the fix.

The setups that catch people out

• A laptop in a docking station. Undock it completely rather than unplugging the monitor cable alone, since docks can present displays in ways that persist.
• A laptop with the lid open next to an external monitor. This is two displays. Either close the lid and use the external screen, or disconnect the external screen and use the laptop.
• A television connected by HDMI to the same machine, even in another part of the room.
• A USB-C monitor that also charges the laptop. Disconnecting it removes your power, so have a normal power adapter ready.
• A tablet used as a second screen through software such as Sidecar or a third-party app. Disable the feature and quit the software.
• A virtual display created by remote desktop or screen-sharing software left running in the background.

That last one is worth checking because it does not involve any physical hardware. Quit remote access tools entirely rather than just closing their windows.

Getting to one display on Windows

• Unplug the cable from the second monitor.
• Open display settings and confirm only one display is listed. If a second still appears, use the detect option to refresh, or restart.
• If you are on a laptop that was docked, undock and then restart.
• Check that no remote desktop or screen-sharing software is running in the background, including anything in the system tray.

Getting to one display on macOS

• Unplug the cable from the external monitor.
• Open the displays settings and confirm only the built-in display is shown.
• If you use a tablet as an extra display, turn that feature off explicitly rather than just disconnecting the tablet.
• Quit any screen-sharing or remote access applications from the menu bar, not just their windows.
• If a display still shows as connected, restart with everything already unplugged.

Restart with everything unplugged

The reliable sequence, if you hit trouble, is to unplug everything first and then restart, rather than unplugging while the machine is running. Some display configurations persist until a restart clears them, and a restart also takes care of the background software that can create virtual displays.

Do this well before your appointment rather than during check-in.

Why connecting a display mid-exam is treated seriously

If the software detects a new display appearing during a session, that reads as a deliberate act. Unlike a failure at launch, which is simply a blocked start, this typically results in the session being terminated and recorded as a violation.

This is worth knowing because it can happen accidentally. A dock waking up, a cable making contact again, or a tablet reconnecting over a wireless display feature can all trigger it. The protection is to disconnect physically and switch off the relevant features, not merely to avoid touching anything.

If you only have one screen but still fail the check

A few less obvious causes:

• Remote access software running in the background creating a virtual display.
• A graphics driver reporting a phantom display, which a restart usually clears.
• Display mirroring to a wireless device such as a smart TV, still active from earlier.
• A graphics driver issue that needs an update, which is not something to attempt on exam day.

Run the system check at least a day ahead specifically so that you have time to work through these.

Planning your workspace

If you normally work on several screens, decide in advance which one you will test on and how you will disconnect the rest. Practical points:

• Test on the screen with the webcam, or with the webcam mounted on it, so your face is centred while you look at the exam.
• Make sure the screen you keep meets the minimum resolution requirement.
• If disconnecting cables means crawling under a desk, do it the night before, not during the room scan.
• Check the remaining display is positioned so you are not turning your head away from the camera to read it, since repeated gaze away from centre gets flagged.

That final point is a small refinement that avoids an entirely separate problem.

System requirements and display-detection behaviour change with each software release. Confirm current requirements against your proctoring platform's official documentation and run the system check before test day.