Just closed yappari and started it up again and I have the same problem.

edit: the only message in the log is:

Connecting to bin-short.whatsapp.net:5222 ...

I can ping bin-short.whatsapp.net ok, but can't open a tcp connection to port 5222 from any of my home computers or from a work one which is on a different ISP. So I am going to guess whatsapp servers just have a problem - unless part of their upgrade to the protocol is also changing the port they use for communication.