Fixing the Black Box When Sharing Content in Zoom


When I use my MacBook Pro1 to share content in a Zoom meeting, it occasionally seems to get stuck. Sharing the screen works fine, for a bit, then it freezes, and then it gets replaced by a black box. I don’t find out until a minute later, when people politely cough and say “so… we can’t see what you’re doing anymore…”

The first time, I figured something just got crosswired somewhere, with Zoom and YuJa and Sidecar all trying to do things with my display. I rebooted, and the problem went away. Then, it happened again, and I figured I should try to figure out how to prevent it from happening again.

Some googling2 turned up similar issues on Windows and Linux laptops, related to graphics cards. And then I saw this page from University of Minnesota’s IT site that lists security permissions and switching the GPU as possible causes.

I checked the security permissions setting, and it was good. So, maybe the laptop decided to switch from integrated graphics to dedicated graphics card while I was sharing the screen, and maybe that tripped up Zoom somehow? There shouldn’t have been a need to switch - the laptop was plugged in, so it’s not an energy saving thing. Maybe Zoom started using the integrated graphics system more, and hit a threshold that moved things over to the dedicated graphics card?

To test it, I went into the Battery settings panel, and turned off “automatic switching”.

macOS Battery settings panel

That means, when I do unplug, I may want to manually switch back to the integrated graphics? Not sure how to even do that.

About This Mac, showing GPU

About This Mac shows which GPU is currently being used: the dedicated Radeon Pro, or integrated graphics.

Anyway. After testing a few times since, it seems to be solid now. This seems like a stupid thing to have to think about, but here I am…


  1. a 2019 15" MacBook Pro, delivered 3 days before the 16" model was announced… ↩︎

  2. DuckDuckGoing, but that doesn’t sound right. ↩︎


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