A black screen almost always means "the session is up but the picture never arrives". The usual suspects are missing permissions (especially macOS), a locked or sleeping host, or a broken graphics driver.
Permissions (mostly macOS)
macOS requires screen recording permission, otherwise the remote side receives a black frame. Restart the client after granting it, and re-check after system upgrades.
- System Settings → Privacy & Security → Screen Recording
- Tick the client and relaunch it
- Check accessibility permission too
- Re-confirm after a system upgrade
Lock screen and sleep
Windows may return a black frame while locked or showing a screensaver; macOS behaves similarly. Keep the machine signed in, or send a wake action inside the session.
- Keep the system signed in
- Disable screensaver and auto-lock
- Disable sleep and hibernation
- Wake the display from the session if needed
Drivers and graphics
A failed virtual display driver, a broken GPU driver or switching between integrated and discrete graphics can all cause black screens. Reinstall the client or update the GPU driver.
- Reinstall the client to repair virtual drivers
- Update the GPU driver to a stable version
- Try switching graphics mode on dual-GPU machines
- Disable hardware acceleration on Windows
FAQ
Only some application windows are black.
Usually protected content such as DRM video, or hardware-accelerated windows. Disable hardware acceleration in that app and reconnect.
Does the web client also show black?
The cause is on the host, not the controller, so the same permission, lock screen and driver checks apply.