Tvheadend

Since no one has given you a better answer yet and I assume you want to get your backend up and running again, I would suggest you take a look at this article, which tells you how to backup and restore your TVHeadEnd configuration:

https://freetoairamerica.wordpress.com/2015/12/12/how-to-move-tvheadends-settings-from-one-system-to-another/

After you have made a backup of your settings (and any other files you want to preserve) and saved them on a different system, you should be able to start over from scratch, by reinstalling the operating system, TVHeadEnd, and any necessary tuner drivers (not needed if your tuners are natively supported in Linux). Then you can restore the settings.

I know it's pain to start over from scratch but sometimes if you have a problem such as this it's faster to just do a full reinstall then to mess around trying to figure out what is causing the problem. I'm running Ubuntu Server 14.04 and TVHeadEnd 4.0.9 and so far am not having problems with it, so if you are running a different version of Linux you could try that combination, or just start over with whatever you've used in the past and see if it still works.

Alternately you could TRY reverting TVHeadEnd to a previous version - I doubt it will help, and if you really want to do it I would save your configuration to another system first, just in case everything goes south on you. But instructions for reverting a program from the command line are shown in the last part of this article (or you can perhaps use the instructions closer to the beginning if you are running a desktop version of the operating system):

http://www.howtogeek.com/117929/how-to-downgrade-packages-on-ubuntu/

I'm no Linux guru by any stretch of the imagination, but I really would be surprised if reverting helps your problem in any way.

Note that none of this will help if it's a hardware problem; you might want to remove any tuner cards and check the connectors to make sure they are still shiny, and use compressed air to blow any dust out of the system, etc. Most of the time when hardware "fails" it's just corrosion or dust/dirt, or a card not seated properly in its slot or something like that. Although another common cause is a bad capacitor (you didn't notice a funny smell coming from your system by any chance, did you?) on a motherboard or card.

Thanks for your reply, I've downgraded and upgrade: no solution. I've switched to my backup-system and will reinstall the main system. Thanks for your reply !

Did you manage to solve this? I seem to be getting a very similar log file to you on crash.

Mine is crashing during recordings only.