I’m also getting this issue using the default theme. There is a problem on this code (archive.php) that trigger unexpected T_OBJECT_OPERATOR
if (is_category()) // If this is a category archive
printf("<h2 class='center'>Sorry, but there aren't any posts in the %s category yet.</h2>", single_cat_title('',false));
else if (is_date()) // If this is a date archive
echo("<h2>Sorry, but there aren't any posts with this date.</h2>");
else if (is_author()) // If this is a category archive
printf("<h2 class='center'>Sorry, but there aren't any posts by %s yet.</h2>", get_userdatabylogin(get_query_var('author_name'))->display_name);
else
echo("<h2 class='center'>No posts found.</h2>");
For the meantime, I removed the code ??