Web API XML Serialization

Question

I am trying to get XML result in Web API but I get the following error:

 

<Error>

<Message>An error has occurred.</Message>

<ExceptionMessage>

The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'.

</ExceptionMessage>

<ExceptionType>System.InvalidOperationException</ExceptionType>

<StackTrace/>

.

.

.

 

 

there is no problem in getting result in JSON format. I specifically need result in XML.