I saw another post with a similar issue but the reply was marked private. Recently the repeater field stopped working. I’ve updated the ACF plugin to v 4.2.1 and also updated to WP v 3.6. Still doesn’t work.
I get this error when it renders in the browser: Warning: Invalid argument supplied for foreach() in /html/wp/wp-content/plugins/acf-repeater/repeater.php on line 894
and this error when I try to edit the posts or custom fields: Fatal error:  operator not supported for strings in /html/wp/wp-content/plugins/acf-repeater/repeater.php on line 418
I’ve tried disabling plugins but nothing is working.