RuntimeException occured : java.lang.RuntimeException: java.lang.ClassCastException: java.lang.String cannot be cast to com.mongodb.DBRef

I have been using play for a few months now on ubuntu servers and also on Google App Engine using the Siena module. Now I have an application on an Ubuntu server with the following versions:

Play Framework - 1.1 Morphia - morphia-1.2beta3

My code is thro开发者_JAVA技巧wing a very strange error:

RuntimeException occured : java.lang.RuntimeException: java.lang.ClassCastException: java.lang.String cannot be cast to com.mongodb.DBRef

for this line inside app/models/Playlist.java:

List items = PlaylistItem.filter("playlist", this).asList();

"playlist" is a field in PlaylistItem and it's defined as:

@Required @Reference public Playlist playlist;

The weird thing is that this same application (I have the code in source control and pull to both machines) works on my laptop but does not work on my Ubuntu server. Does anyone know why this may be happening?

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you may want to check this bug report. It seems to be your issue.