User Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

Not sure if it's a bug or feature, but setting the "browser.urlbar.suggest.searches" preference in about:config to false disables the "?" functionality of the address bar described at https://support.mozilla.org/en-US/kb/address-bar-autocomplete-firefox, section "Changing results on the fly", that is you type something like "? test", but no list of search suggestions appears.

This seems strange, because turning off the related preferences "browser.urlbar.suggest.bookmark", "browser.urlbar.suggest.history" and "browser.urlbar.suggest.openpage" does not disable the operation of the "", "^" and "%" prefixes respectively, i.e., you can set "browser.urlbar.suggest.bookmark" to false and still get a list of bookmarks matching "test" when you type " test" in the address bar.

Perhaps it should work the same for "?", that is, regardless of the "browser.urlbar.suggest.searches" value the user should be able to get a list of search suggestions by explicitly using the prefix.

Sorry, the message got messed up because of the unescaped * characters. This is the correct version:

Not sure if it's a bug or feature, but setting the "browser.urlbar.suggest.searches" preference in about:config to false disables the "?" functionality of the address bar described at https://support.mozilla.org/en-US/kb/address-bar-autocomplete-firefox, section "Changing results on the fly", that is you type something like "? test", but no list of search suggestions appears.

This seems strange, because turning off the related preferences "browser.urlbar.suggest.bookmark", "browser.urlbar.suggest.history" and "browser.urlbar.suggest.openpage" does not disable the operation of the "*", "^" and "%" prefixes respectively, i.e., you can set "browser.urlbar.suggest.bookmark" to false and still get a list of bookmarks matching "test" when you type "* test" in the address bar.

Perhaps it should work the same for "?", that is, regardless of the "browser.urlbar.suggest.searches" value the user should be able to get a list of search suggestions by explicitly using the prefix.

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Thanks for filing, this is fixed by bug 1648385 in Firefox 79.