You have no doubt noticed that federation is breaking again. I am painfully aware of it. The issue is with the symphony queue runner that processes incoming messages from other instances. Occasionally, the server receives a message that causes the queue runner to die. I have to manually remove the offending message out of rabbitmq. The message does not appear to be malicious, rather there is something malformed in an otherwise legit looking post that causes the queue to die. I am working with the mbin team to track down what it is about the messages that causes the problem, but sadly until I there is a fix, this is going to keep happening