I updated to Android 11 today and perftest fails with:

[2020-09-24 13:57:33] INFO: Run tests on Pixel 2 using Android version 11
[2020-09-24 13:57:33] INFO: Running tests using Firefox - 25 iteration(s)
[2020-09-24 13:57:33] INFO: Browser failed to start, trying 2 more time(s): adb error: couldn't create file: Permission denied
[2020-09-24 13:57:34] INFO: Browser failed to start, trying 1 more time(s): adb error: couldn't create file: Permission denied
[2020-09-24 13:57:34] INFO: Browser failed to start, trying 0 more time(s): adb error: couldn't create file: Permission denied
[2020-09-24 13:57:34] ERROR: BrowserError: Could not start the browser with 3 tries
    at SeleniumRunner.start (/Users/mcomella/.mozbuild/browsertime/node_modules/browsertime/lib/core/seleniumRunner.js:86:13)
    at process._tickCallback (internal/process/next_tick.js:68:7)
[2020-09-24 13:57:34] ERROR: No data to collect

It seems there may have been some file permissions changes.

acreskey thinks this might be a dupe of bug 1650891 but I filed a separate one just in case it isn't.

Given bug 1650891 is closed, I tried again with geckodriver 0.28 and fenix crashes on startup. This could be the same root cause as bug 1680407.

There's a Nightly start up crash in fenix from 12/3+ so use prior builds (in the short term) for testing.

Using the latest GeckoDriver in m-c, I believe the root cause of this issue is https://bugzilla.mozilla.org/show_bug.cgi?id=1680407#c8 so I'm going to dupe to that.