Braintree

1. Open app/design/frontend/base/default/template/braintree/form.phtml and find the following lines:

if ($$('#onestepcheckout-form').first() && !loggedIn) {
    $('id_create_account').observe('change', function() {
        $('_store_in_vault_div').toggle();
    });
}

2. Replace them with :

if ($$('#onestepcheckout-form').first() && !loggedIn) {
    $('id_create_account').observe('change', function() {
        $('_store_in_vault_div').toggle();
    });
} else if ($('firecheckout-form') && !loggedIn) {
    // do nothing
}

3. Save the file and clear cache.

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