IMHO this may be a network problem. If this is the case, following may help.
If your server is becoming unresponsive after seeing this error frequently, try setting
ConnectionIOTimeout of your HTTP transport to a lower value (for example 1 sec instead of default 5 seconds). You will still see these exceptions for bad requests but server shall stay more responsive, as your webcontainer threads will be blocked for a shorter duration before timing out on a bad request. If you don't have responsiveness issues but just irritated by this exception every once in a while, you may increase this value to give more slack to cover for network problems.