Firefox users and session loss bug/nan

If you see the error message below, and you are using the Firefox browser, then it might be because of a known browser bug. The steps to fix it, are below.

The same problem with the SeaMonkey (Mozilla) browser can be fixed the same way, only remember to restart your browser afterwards.

Firefox 71+
(There might be a warning screen after this. Continue only if you are an experienced user) Otherwise select "Number" and click the plus icon
 * 1) Open a new tab or window
 * 1) type or paste   in the address bar, and click "Enter".
 * 1) type or paste   in the search bar
 * 1) if the preference exists, click the pencil icon to edit it.
 * 1) enter a value (see below), and click the tick icon to save
 * (You might need to reload the page, or re-log-in, or restart your browser, for the fix to start working. But probably not.)

Firefox 70 hām koh-khah kē ê pán-pún

 * 1) Open a new tab or window
 * 1) type or paste   in the address bar, and click "Enter". (There might be a warning screen after this. Continue only if you are an experienced user)
 * 1) right-click anywhere in the table of results (pay attention not to alter the existing data)
 * 1) suán-ti̍k "Sin-ê"
 * 2) suán-ti̍k "Tsíng-sòo"
 * 1) type or paste   as the preference name, and click "OK"
 * 1) type a value (see below), and click "OK"
 * (You might need to reload the page, or re-log-in, or restart your browser, for the fix to start working. But probably not.)

Value: any number between 200 and 2000 should work fine. Estimate 5+ cookies per wiki, and only count the project (e.g. Wiktionary) that you access the most languages of.

Iân-sin tsu-sìn

 * T151770
 * https://bugzilla.mozilla.org/show_bug.cgi?id=1319403