The reason is that the "fingerprint" settings-subpage is not specifying which UI element is triggering it, causing an assertion error (see attachment).

Deleted: associated_control_missing.png 31.5 KB

	associated_control_missing.png 31.5 KB View Download

@stevenjb: At first glance, the fingerprint subpage is a sub-sub-page, which makes it hard to properly display the search bubble that guides the user to that subpage. Specifically
 - the subpage resides at https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/people_page/people_page.html?l=339.
 - The associated control resides at https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/people_page/lock_screen.html?l=61.

This is not something that is currently handled. The only other UI with sub-sub pages is content settings, which handles it by having the sub-sub pages not be searchable (using no-search attribute, example https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/privacy_page/privacy_page.html?l=212).

So the easiest way to fix the error is to add a no-search attribute for now. That would mean that the contents of the /lockScreen/fingerprint sub-subpage will not be searched, but perhaps that is good enough (since the subpage leading to the sub-subpage is still searched).

Also I just realized that the /lockScreen subpage is already annotated with no-search [1], which makes a no-search in the /lockScreen/fingerprint sub-subpage even more justified.

[1] https://cs.chromium.org/chromium/src/chrome/browser/resources/settings/people_page/people_page.html?l=330

Upgrading this to a P1

Will fix this together with  issue 695195