Usually that exception is a side effect of the load.
The increased load could be due to openHAB trying to apply addon changes every minute.
Can you post the contents of the following files?
/etc/openhab2/services/addons.cfg/var/lib/openhab2/config/org/openhab/addons.config
It may help to delete /var/lib/openhab2/config/org/openhab/addons.config so it is regenerated with correct content (see [SOLVED] OH 2.3 missing ComfoAir Binding in PaperUI).