I have observed that sometimes hitting the relations tab will return a 404 error from Tomcat. This seems to happen most frequently when it is pressed within 30 seconds of creating/uploading a new file in Nuxeo. The error looks like this:
HTTP Status 404 - /nuxeo/nxdoc/MyRepo/8e5fc580-ddad-4942-b1a7-1b200982bf50/view_documents
type Status report
message /nuxeo/nxdoc/MyRepo/8e5fc580-ddad-4942-b1a7-1b200982bf50/view_documents
description The requested resource (/nuxeo/nxdoc/MyRepo/8e5fc580-ddad-4942-b1a7-1b200982bf50/view_documents) is not available.
Apache Tomcat/5.5.20
Clicking reload when this appears will usually cause the correct thing to be displayed.