I recently upgraded to macOS Catalina. I use a setup with Karabiner Elements and Hammerspoon, so I can switch between apps using shortcuts like Caps-Lock+Letter.

My caps-lock is configured to act as a 'Hyper' key when held down, meaning its the same as pressing command + option + control + shift.

However after Catalina upgrade, whenever I press caps-lock + W, the screen flashes.

It also happens when I press the keys individually, so command + control + option + shift + W, so I believe it is some new shortcut introduced in Catalina that does this.

However I can't seem to find what it is and how to disable it, could anybody please help?

The flash is the same as the flash you see when you go to System Preferences > Accessibility > Audio > Test Screen Flash.

2 Answers 2


WiFi Diagnostics Keyboard Shortcut in macOS Catalina

It looks like cmd+ctrl+option+shift+w triggers a WiFi Diagnostics session.

Browse to /Private/var/tmp and you'll see 300MB+ files titled WiFiDiagnostics_YYYY-MM-DD_IP4-address_Mac OS X_MacModelName.tgz

I can't find any official documentation on this, and I believe this is new for Catalina.


Unfortunately, I don't yet have a solution to this problem. I can confirm that it manifests on my Catalina system as well. I wanted to add a comment but don't have enough reputation (any advice on how to better approach this is welcome).

Back to the issue at hand, on my 13" 2019 Retina MBA I can see the same problem. It is as if we're pressing a magic combo which seems to trigger a debugging session of sorts. The processes related to this, that I could find, are footprint, lsregisterd, spindump, system_profiler, sysdiagnose and wifivelocity. On this system, being a 2-core one, the CPUs go up to 100% and sit there while these processes run and do their thing. I had to resort to some shell magic to kill these to make it stop faster.

I have also asked a friend to press the combo on a 2016 MBP and I can confirm the system did the same thing, screen blinking, footprint process running, etc.

Does anyone have an idea on being able to reclaim this shortcut?

  • Welcome to Ask Different. Please refrain from adding comments in the Answer section. This is for answers to the questions only. If you have a different question, you can ask it by clicking Ask Question. You can also add a bounty to draw more attention to this question once you have enough reputation. See How to Ask for more info on how to ask a question. - From Review
    – fsb
    Nov 5, 2019 at 18:21
  • Thanks @gm! It was a good instight, it indeed seems to run sysdiagnose, but its confusing, because the shortcut for that is cmd+ctrl+option+shift+. and not w
    – mirosval
    Nov 6, 2019 at 13:51

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