You will encounter this error when using browser mode IE9, 10 or 11 (as opposed to IE9, 10, 11 compatibility mode) on pages where you call the dialog window for the SharePoint 2010 people picker e.g.:
- when selecting admin for a new site collection being created,
- when settings alerts on the list and selecting a user,
- when creating a task item in the list and selecting assignee, etc.
This will as well happen in EFI products when e.g.:
- creating a course offering in REM you select a course,
- when creating a filter in a custom REM report and selecting a teacher,
- when creating a conference and selecting participants in picker, etc.
It appears that this has to do with IE9, IE10, IE11 document standards for the client's browser. From what our investigation shows the picker dialog window is treated as if it's opened in IE5 quirks mode and therefore required scripts don't work on this page and result in an error.
To learn more see this discussion.
We haven't been able to find any hotfix released for this matter, however, we verified a quick solution suggested in an article from the link above to force the picker page load IE 8 Standards in the page:
meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8"
<meta name="GENERATOR" content="Microsoft SharePoint" />
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" />
A client-site workaround is using browser compatiblity mode as suggested in our article.