My site has had some issues since auto-updating it’s WordPress core to the latest 4.2 – as the theme it uses (Simplissimo) is not strictly compatible with that version.

The main issue was error messages appearing at the top of each page – but after a bit of investigation these were found to be just general error messages caused by plugin(s).

error messages appearing

This link was useful –

And using the info in there, I changed the sites wp-config.php as follows:
define(‘WP_DEBUG’, true); to define(‘WP_DEBUG’, false);

No more error messages.