I had an open tab of our website ( http://dev.ripple.foundation:8000 ).
Then I log in to http://dev.ripple.foundation:8000 and moved to http://dev.ripple.foundation .
After I tested some issues there, I returned to http://dev.ripple.foundation:8000 .
And there I get the message that I have to re-login, and after I log in I got the following error message:

Try to reproduce the error.