In one of the applications I was working lately, one usual day I was informed that the people picker suddenly stopped working across the site. It sounded very weird at first. After reviewing all the changes that were done recently in the site I found that the custom master page the application was using was updated to support IE9 compatibility which was breaking all the people picker controls in all the pages. So changing back it to IE8 fixed the issue.
Not compatible –
<meta http-equiv=”X-UA-Compatible” content=”IE=9″/>
Change it to –
<meta http-equiv=”X-UA-Compatible” content=”IE=8″/>