--- a/server/session.py	Thu Jun 06 09:44:37 2013 +0200
+++ b/server/session.py	Thu May 23 19:25:24 2013 +0200
@@ -865,6 +865,8 @@
         Transaction is created if necessary"""
         with self._lock: # no transaction exist with the same id
             try:
+                if self.closed:
+                    raise SessionClosedError('try to access connections set on a closed session %s' % self.id)
                 tx = self._txs[txid]
             except KeyError:
                 rewriter = RQLRewriter(self)