Recently I’ve encountered multiple issues at different client sites that all led back to SharePoint / Internet Explorer compatibility problems. On two entirely separate farms, SharePoint 2010 was generating a correlation error when someone attempted to select a user from the People Picker:
System.InvalidOperationException: Namespace prefix ‘xsd’ is not defined. At System.Xml.Serialization.XmlSerializationReader.ToXmlQualifiedName(String value, Boolean decodeName) at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderDictionaryEntryArray.Read1_Object(Boolean isNullable, Boolean checkType) at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderDictionaryEntryArray.Read2_DictionaryEntry(Boolean checkType) at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderDictioaryEntryArray.Read3_ArrayOfDictionaryEntry()
Additionally, a number of weird, unexplainable problems were occurring. These ended up disappearing when users changed the browser mode from IE9/IE10 to IE8 in F12 developer tools. Obviously, then, the source of the problem lay in some sort of compatibility issue between SharePoint and Internet Explorer 9 and/or Internet Explorer 10.
To fix browser incompatibility problems, I found a number of people on forums and blog posts recommending the use of the “X-UA-Compatible” declaration inside a meta tag placed inside the head. For example:
<meta http-equiv=”x-ua-compatible” content=”IE=8″ >
As best effort and how the problem is in the pickerdialog.master and the People Picker is using the pickerdialog.master file, you need to add the following line in the head element.
meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8"
<head>
<meta name="GENERATOR" content="Microsoft SharePoint" />
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" />
....
</head>
Followed by iisreset this should solve the problem in People Picker
Albandrod's Memory 