Unable to watch a page/space/wiki

Steps to reproduce:

-Login
-watch space/page/wiki

Refresh the page. You will see that the settings are not saved. By looking at the console you see something similar with:

org.xwiki.velocity.XWikiVelocityException: Failed to evaluate content with id [/templates/watch.vm]
at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:204)
at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:160)
at com.xpn.xwiki.render.XWikiVelocityRenderer.evaluate(XWikiVelocityRenderer.java:116)
at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:1840)
at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:153)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:224)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:115)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:129)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.xwiki.wysiwyg.server.filter.ConversionFilter.doFilter(ConversionFilter.java:152)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.xpn.xwiki.plugin.webdav.XWikiDavFilter.doFilter(XWikiDavFilter.java:68)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:218)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:112)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:536)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:915)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:539)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:405)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: org.apache.velocity.exception.MethodInvocationException: Invocation of method 'addWiki' in class com.xpn.xwiki.plugin.watchlist.WatchListPluginApi threw exception java.lang.UnsupportedOperationException at /templates/watch.vm[line 11, column 20]
at org.apache.velocity.runtime.parser.node.ASTMethod.handleInvocationException(ASTMethod.java:243)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:187)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:369)
at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
at org.apache.velocity.runtime.parser.node.ASTElseIfStatement.render(ASTElseIfStatement.java:92)
at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:195)
... 40 more
Caused by: java.lang.UnsupportedOperationException
at java.util.AbstractList.add(AbstractList.java:148)
at java.util.AbstractList.add(AbstractList.java:108)
at com.xpn.xwiki.plugin.watchlist.WatchListStore.addWatchedElement(WatchListStore.java:464)
at com.xpn.xwiki.plugin.watchlist.WatchListPluginApi.addWiki(WatchListPluginApi.java:218)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
... 47 more
2011-05-30 13:02:44,355 http://192.168.2.17:8080/xwiki/bin/skin/resources/js/scriptaculous/effects.js ERROR c.x.x.w.XWikiAction - Connection aborted