InvalidServerResponseException: Character reference "&#x1" is an invalid XML character

[pawc]

I get this exception stack when trying to get a WorkItem object with line below
workItemClient.getProjects().get("MyProject").getWorkItemClient().getWorkItemByID(someNumber);
It seems to be thrown only for a particular ID. From its content I cannot tell how this workitem is different from the ones that work. Any ideas what could cause that?

com.microsoft.tfs.core.ws.runtime.exceptions.InvalidServerResponseException: javax.xml.stream.XMLStreamException: ParseError at [row,col]:[1,28930]
Message: Character reference "&#x1" is an invalid XML character.
at com.microsoft.tfs.core.ws.runtime.client.SOAPService.executeSOAPRequestInternal(SOAPService.java:617)
at com.microsoft.tfs.core.ws.runtime.client.SOAPService.executeSOAPRequest(SOAPService.java:444)
at ms.tfs.workitemtracking.clientservices._03._ClientService5Soap12Service.getWorkItem(_ClientService5Soap12Service.java:622)
at com.microsoft.tfs.core.clients.workitem.internal.WorkItemImpl.open(WorkItemImpl.java:259)
at com.microsoft.tfs.core.clients.workitem.WorkItemClient.getWorkItemByID(WorkItemClient.java:248)
at [my code...]