People Picker to add users to SharePoint 2010 group - Namespace prefix 'xsd' is not defined

Hi All,

We have recently migrated from SharePoint 2007 to SharePoint 2010. Upon trying to add users to SharePoint group, we got the below error:

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.XmlSerializationReaderDictionaryEntryArray.Read3_ArrayOfDictionaryEntry()

The problem here is we have a known issue with people picker not working properly in IE9..

Possible Resolutions:

Solution 1 (Temporary Solution)

Change the Document Mode to IE-8 using IE - developer toolbar as shown below

Solution 2 (Permanent Solution)

In System master page, change the content attribute in meta tag from IE-9 to IE-8 as shown below.

<meta http-equiv="X-UA-Compatible" content="IE=8"/>

Hope this helps some one. Thanks !!!