Serial bridge stops processing messages

A few weeks ago finally upgraded my system from 3.0.2 to 3.1. The eBus binding is compatible in the mean time, and opentherm no longer gives me faults (showing offline, but still being online) as it did in 3.0.2. So far I am happy. Unfortunately the serial binding still stops processing messages every few days. Sending messages from openhab with the serial binding does not help. The behavior is still the same as in the first post.