All recordings are gone after update from 4.0.9 to 4.2.1

I've upgraded my tvheadend by adding the stable-4.2 to my repository and install it by apt-get install tvheadend. But after the update, all recordings in the "Finished Recordings" are gone. The configuration is the same, he even shows me my failed recordings, but not my finished recordings.

I was a little bit shocked, that there is no function to import old recordings. So how can i update tvheadend and keep my recordings ?