You can possibly use an "Options + Shift" shortcut as holding only Options will trigger Troubleshoot Mode. On Windows this is the Shift key and thus less likely to cause issues.

Hmm, I assume the problem is that Firefox starts so quickly that it detects you are still holding down option/alt. (Otherwise, why would Firefox receive the option/alt key at all?) Is it possible to build in a delay so you have time to release the key before Firefox launches? In a bit of searching, it appears there is a "delay next action" option, but I don't know whether you can delay the initial action.

If you do not need to use Safe Mode then you can disable this troubleshooting feature via a policy.

• https://github.com/mozilla/policy-templates/blob/master/README.md

@cor-el, I appreciate your suggestions. I tried to use policies, but it didn't work. According to https://support.mozilla.org/en-US/questions/1226264, it seems that DisableSafeMode only works using Windows GPO.

Adding Shift was not enough either.

@jscher2000, your delay suggestion worked, although it is a little inconvenient. Anyway, thank you!

Finally found a solution: https://github.com/mcandre/dotfiles/blob/master/setenv.MOZ_DISABLE_SAFE_MODE_KEY.plist

Source: https://stackoverflow.com/questions/10111026/disable-change-firefox-safe-mode-hotkey-shift/47252708#47252708

Tested. It works perfectly.