Trying to view the draft site when not logged in (happens when FireFox saves open tabs before closing) I got the following error (version 2.2.3):
XML-parsefout: onjuist gevormd Locatie: http://www.mydomain.nl/Security/login?BackURL=%2F%3Fstage%3DStage Regelnummer 44, kolom 105: <p>You must log in with your CMS password in order to view the draft or archived content. <a href=\"/home/?stage=Live\">Click here to go back to the published site.</a></p>
I found the solution in the language file en_US.php (5):
$lang['en_US']['ContentController']['DRAFT_SITE_ACCESS_RESTRICTION'] = '... <\"%s\" ...';
This line is surrounded by single quotes that will not 'interprete' the escaping backslashes surrounding %s. Solution: use double quotes or remove the backslashes, both seem to work. This applies to other language files as well.